1996 Chevrolet Corsica has some idle and transmission issues
 

Hello all!

Bought a 1996 Corsica from the auctions for $175, obviously it has some issues here they are:

It runs really really good when cold, it fires right up on the first crank and idle smoothly, goes into gear smoothly everythings great! Once the coolant gauge reaches 1/4 of the way up (read below) at idle it will keep trying to shut off. The headlights will dim and it'll catch itself and idle back up. My scan tool had idle going from 650+ to less than 550. It'll do this several times per second. It has not stalled yet but it seems to be getting worse. There are cobwebs in the engine bay and the plug wires have a few cracks in the boot going to the plug. I am changing these today. (why so hard?!??!)

The coolant gauge hovers at 1/4 of the way. My scantool says 1/4 is 185 degrees. 1/2 is 225! I read online that these motors actually are designed to run at this temperature as that's when the fan turns on. Doesn't go above 235

The trans is a weird situation, when I bought it after the engine warmed up the TC would stay locked and it would violently stall when coming to a stop. It would fire back up and I'd have to neutral slam it to get it to move. I solved this by simply unplugging the TCC solenoid (blue wire on top of transmission). This made me lose 4th gear for some reason. I'm guessing it's a computer issue not letting the trans shift into 4th. This equals 3100rpm at 70. Yuck. The trans shifts smooth as butter otherwise.

I watched the fuel trims and I vaguely remember it staying at -2.x at idle and 0 at 2500rpm. 18mg of vacuum at idle, all this is according to scan tool.

I replaced the IAC valve due to getting an idle speed too high code and the code went away for 1 day and came back same code.


Any advice? Sorry for asking for so much.