My old automatic transmission is acting funny

And I'd like to know why...

1969 Mercedes 200 automatic (4-speed)

In the morning start, during the warmup the car will be in park.  The car will initially start and idle and I use the throttle to warm it up since my cold start circuit doesn't function properly.  After about 10-15 seconds of what we can call "high idle" (maybe 2krpms?) the engine begins to act like it's under a load.  More throttle input only makes it more obvious that the engine is definitely under some sort of load (I can probably floor it, and it most likely wont redline.  Almost like the car was on a dyno). 

The car isn't trying to move in either direction when it does this (not forward nor reverse) and moving the shifter from park all the way down to 1 and back up makes the problem go away (and the engine is free to rev again).

Also, but possibly unrelated, there have been a couple times when I put the car in reverse from park and it tried to go forward.  Again, only in the morning and cycling the shifter through the gears stops the bad behavior.

Can anyone tell me what in the world is going on and why?

Last trans fluid flush was in September.  New filter too.  Old fluid looked great, new fluid still looks good.

Thanks

a sticking valve in the body is likely , it's trying to be in 2 gears at once in this case reverse and drive.  I AM NOT A Tranny trouble shooter, when you drop it to Low you either pull the valve or changed fluid direction enough to unstick it.

+1 on the sticking valve.

Wow.  That is not nearly as bad as I thought it would be.  As it so happens I have a valve body repair kit on hand.  

Think that'd do the trick?

Try some Marvel Mystery oil.   It worked on Hydamatics when they would not down shift when coming to a stop.

Interesting!  How much MMO  are we talking about?  1/4 quart or so next time it's low?

Hungary Bill said:

Interesting!  How much MMO  are we talking about?  1/4 quart or so next time it's low?

How much fluid does the trans hold?  If it holds 12+ quarts from a dry fill, I'd probably throw a whole quart of MMO in it.  

On it!  Thanks guys.

Now to find some MMO.... 

Congrats! Your car accidentally added a transmission brake, a sought after piece of hardware for drag racing!

But yeah, it's a sticky valve or o-ring or something in the valve body. 

Well, I don't mean to brag or anything but with this here transmission fault...er....  modification in place, I got my Merc's  1/4 mile times down low enough to put away the calendar and break out the stop watch  

0-60?  eventually