1988 L98 350... 88 formula.
I ditched the auto, now have a T5 in the car. It is custom tuned and is running good. I cleaned the IAC out and problem still exsits.

What it does :

Idles great, drive along, car will idle at 2000rpm, give a quick rev, falls back to normal, eventually a small rev does nothing and will hold at 2000RPM.

Shut it off, let it sit, restart and its fine. Sounds like TPS to me, but may be wrong.

Only SES is for 24 VSS, mech, trans and im elec. so I need adapter, but it does this with engine light on or not. SO I know its not that, and if it was that it would do it all the time due to no VSS signal.

Any input!?

 

I did the same thing as you with the tranny swap and had the same problem. I had to set my timing back to the recomended setting and my tps was out.