This thing is driving me bugE36 M3.
Okay, the latest: worked out two bugs, one was a poor connection at the leading ignition trigger lead, i was losing leading spark at inopportune times. Got that fixed. Got the damn thing running well enough to be able to set the ignition timing (set it at a max of 25 degrees advance at 3500 RPM) and then discovered I had no 12V power to the idle air control. Two wiring problems. My wiring guy is an idiot. Where's the 'embarassed' emoticon when ya need it? 
Checked the vacuum, it sits at around 15" at idle, which is pretty close to right for a rotary. But it still idles like crap. I swapped in my spare ECU, still idles like crap. Yanked the (brand new) plugs, the leading plugs are bone white (lean). So now I have gone 180 degrees from the original problem.
In desperation, I tried pinching off the fuel return line, just to see what would happen. It was at ~40PSI (spec is 39.8) before I pinched the line, as the pressure rose it ran better and better, at 55-60 PSI it ran great. It continued to run fine as the pressure kept going up, at ~90 PSI the fuel pump fuse blew. Replaced the fuse and started the engine, still runs like poop at 40PSI. I checked the flow at the fuel return at the cell, it sounds like a garden hose in there so no problem with pump delivery as far as I can tell.
So the primary (and secondary) injectors will have to come back out for yet another look, along with the pulsation damper. I have some more injectors which I have tested and reverse flushed that I plan to install. Any other ideas?
J, was there any RF isolation on the original car. Maybe you are getting alternator noise at the ECU causing it to act wonky. Shooting in the dark at this point since you have checked everything else.
What are you using for a fuel gauge? Is it removable or fixed? Check it against another unit. If it is accurate then see how it runs at 57psi. We did some work on a modified NA 1986 car and it would not run without the pressure jacked up.
The RF insulation was only around the CAS and MAF wiring, I left it intact.
The fuel pressure gauge is a removeable diagnostic piece I have had for some time now.
Interesting to know you ran across another NA which required greater than stock fuel pressure. When you say 'modified', how 'modified' was it? On this one, I'm running a set of headers and 3" exhaust, the intake is stock, the engine intake and exhaust porting is stock but I have removed the 6th port 'sleeves' so the 6PI ports are open all the time. From what I gather, that's similar to a mild street port (like a mild cam in a piston motor) and allegedly an increase in fuel volume is not required, i.e. the ECU and injectors are up to the job. It's supposed to make the engine idle a bit rougher and there is some bottom end torque loss but that's about it. On the other engine, the 6PI sleeves were in place but turned and locked to the open position.
Well, seems I have found it. The engine has a MLS (multi layer steel) intake gasket and it has a vacuum leak. Looking back, all of the symptoms (except one) were present.
The strangest thing about it and this is the missing symptom: there was no hiss normally associated with a vacuum leak. Instead, intermittently there was a noise very similar to a belt squeak. I was listening very closely, kept hearing the squeak and that could drown out other noises, so I swapped another belt. Same squeak. So I shot a little carb cleaner at the noise, the noise went away and the engine steadied out. Huh?
Almost directly behind where I sprayed is the front of the intake. Shot a little more directly at the part line, it runs great until it's sucked through.
Sometimes I R stoopid.
Nah. You're not stoopid. Just a lotta things to check one at a time until you find the boo-boo. Murphy was working overtime when he inspired the Rotary, with its tip seals and splitcase construction and ported cases. Work great until they don't, and then you scratch your head for a week trying things.
A co-worker drove a RE pickup as his go-to-work rig, and he ALWAYS carried 3 spare sets of plugs. He could change a set of fouled plugs in about 2 1/2 minutes. One day when the goofy thing was running particularly ratty, he used up all his spares on the way to work (about 20 miles) and had to borrow the plug cleaner (when they still had one...) in the Auto shop, so he'd have some spares for the trip home that day. It was that memory that advised a zen-ish attitude. Keep your wits about you, and even a rotary can't fool you for long. 
Got the lower intake sealed to the side of the motor (had to make a gasket).
But now I find these damn things can leak vacuum EVERYWHERE. The primary injectors go directly into the center 'iron', and the injector seals are known to get brittle and not seal properly. So now the intake has to come off AGAIN. ARRRRGGGG.
And again, not a single abnormal noise. No hiss etc, it just idles like crap until you spray carb cleaner directly at the primary injectors.
