Please help me NOT pull an engine (broken bolt content)

So, I decided to replace the IAC on my 98 grand cherokee (360 engine). A few 'while I'm in there's' later and I'm kinda screwed. I wanted to pull the intake because the lower plenum gasket is leaking. Well, despite my best efforts at being careful, the two front and the two rear bolts broke for the intake. 
The two rear bolts are under the cowl, and are going to be VERY difficult go get at. Maybe if I remove the motor mounts to lower the engine, then cut down a drill bit I can get at them, but good luck getting a centered hole!!  

Over the last week or so I've keept them soaking in zep 2000 (best penetrant I've ever used) and have come out a few times a day and taken an air hammer to the intake where the bolts are broken. 
Nothing.
I've also used heat on the intake and an air hammer to the intake.
Nothing. 
I then repeated the above steps but with an upper engine support (fender-to-fender) to apply upward pressure. More Zep, more heat, more air hammer.  
Nothing.  
So today I get the drills out. One hole looks good. Close enough to center to work. I drilled down about 1/2 way (trying to leave some bolt left so I can remove it when the intake is off). The other hole, not soo much. The bolt broke anything but flat. I used a carbide burr to try to flatten it, but it was below the intake manifold surface. that hole drifted way off center and now, any attempt at drilling is like using an end-mill on an engle. The drill is just walking into the intake manifold. 

I'm kinda screwed at this point. The way I see it, I have three options:

1 - put it together and drive it because that intake isn't going anywhere haha.
2 - pull the engine (and have plenty of other bolts break in the process) to try to get access to those rear bolts. If the bolts didn't break off flat, I'm no further ahead.
3 - Cut the intake off around the 4 bolts and remove it piece by piece. It's a wet valley, but I think the 4 bolts are outside of the valley.  

Any other ideas? I don't want to pull the engine due to room and not having a cherry picker anymore. I don't want to tow it to a shop because it's going to be a blank check repair. Is there a way to chemically break galvanic corrosion?

If I'm reading correctly, the bolt heads broke off, leaving the shank of the bolt stuck in the intake, and you can't get the intake off because the bolt shank is stuck in it.

Been there, although not with all four...

You are going to have to commit to it, and beat a prybar in the flat surface at the front of the manifold, against the block, and wiggle until the manifold starts to move.  Once the front moves, you can probably keep wiggling until it breaks the corrosion at the rear.

How much heat?  Oxy Acetylene heat, ot heat gun heat?

Something else might well break, so check ebay for a used manifold.

Edit:  I'm not sure what chemical would eat aluminum oxide, but not aluminum...  If you figure it out, let me know.

In reply to Streetwiseguy :

Yeah, you pretty much have the situation nailed. I'm ok with destroying the intake. I mean, I'd rather not, but I know it might just happen. Honestly, I hadn't thought about hammering a chissel or similar between the block and the intake th break the bond.  
As far as how much heat, only a propate torch. I do have an oxy/acet setup, but didn't know if I really needed that much oomph.  

I'd go more screw driver-ey than chisel-ey with the wedge, and see if you can focus the flame right on the end of the bolt.  Get the bolt red without having a small stream of molten aluminum running down the engine would be ideal.

Good luck.

This will be good practice for the next time you need to change a timing chain cover on an old Ford Windsor.

Two questions for you. If both are yes I would treat this like a broken LS header bolt.

1. Is the intake manifold aluminum?

2. Did just the bolt head break off?

If that's the case I would apply heat and PB Blaster liberally, then weld a nut to the stuck bolt, apply more torch and then zip it out with an impact.  If you can't fit an impact in there give the area around the bolt some percussive maintenance before trying with a wrench.

Got a welder? Tried welding a nut on top of the bolt?  The bonus to this is that the heat from welding can help free up the bolt.  If no welder, check craigslist for someone that does mobile welding.

I've also had good results using a putty knife before a screwdriver.  If you can stack two putty knives you can then slide the screwdriver between them to lessen damage to the mating surfaces 

Worst Case Ontario can you cut the aluminum manifold away with a die grinder and then spin the bolts out?  Chances are the bolts will spin just fine out of the iron block.  You may have to pull the manifold out in pieces.

Prying it isnt gonna get you anywhere and heat isnt either.  Your best solution is going to be to destroy the manifold to free the studs.  Last ditch effort would be to try to dissolve the iron bolts using alum, but its an all day pack a lunch sort of process. 

I have had success with using a piece of thin music wire to clean around snapped bolts. I use something in the .020-.030 range. Cut it with a wire cutter to leave a sharp end. Then I chuck it up in a drill and run it down beside the bolt. This will clean the corrosion out and allow the penetrant to soak in. The music wire is stiff and hard enough to drill without bending and flexible enough to get into places you can't get to straight on. 

Powerhead bolts on Evinrudes come to mind. I fought one of those for over a week before I got that engine apart. 

I meant to post pics, dun forgot. The bolts broke below the surface of the aluminum intake. I can't weld a nut to it. 
I'm going to try a thin wedge, and the music wire. 
 

In reply to DrBoost :

Post the pics?  I might have another option depending on what it looks like.

Welding a nut would be a lovely thing, except there is about two inches of steel bolt being compressed by a thick layer of aluminum oxide.

I remove lots of busted bolts by welding, but this isn't a good application of that skill.

The music wire trick should work. I have also used K&S brass tubing with teeth cut into the end. With that you have to be able to get straight on the bolt.

If you need welding call me. Otherwise  good luck. I hope all else is going well for you.

Braden

All I can offer is prayer.....

If all the bolts are vertical like that one, you should be able to get it. Toyman's trick sounds like a winner, 

Whomp it with a rubber mallet. PB blaster, or some such. Gentle prybarring. You can do it. Walk away when you need to.

I'd clean out around it like toyman says and then call braden.  I've welded nuts to worse

Those intakes aren't uncommon. I'd probably just break it off. The main thing will be not damaging the head surfaces in the process. 

Patrick (Forum Supporter) said:

I'd clean out around it like toyman says and then call braden.  I've welded nuts to worse

Once the intake is lifted off, the bolts will come out with a decent pair of pliers.

I'm enthused about the piano wire idea.  I will remember that.

In reply to Patrick (Forum Supporter) :

I've found when welding on to an steel stud/bolt like the one above the weld doesn't stick to the aluminum. I usually just build up a tower on top until it protrudes above the surrounding aluminum and then grab it which the vice grips.

I have these super cool 90 degree angle adapters that have tiny bits that screw into the head so the total height is around 3-4". 
 

if you'd like to borrow one I can send it to you. 

So the bolts are vertical?  Then you should be able to pop the intake up and off without destruction.  I didn't think about that till i took a closer look

I liked the way mazdaduece hammered razor blades between the parts he wanted to separate to get the initial gap.