My T56 swap put the car out of comission for 2 months, and was not run during that time. After getting everything back together, it runs with a rough idle, jumping around in the 700 - 400 RPM range. The car even stalls when I put it in neutral when coming to a stop (sometimes).

I just filled up with new gas, and it didn't seem to help. The only other thing that I can think of is that I did not tighten the exhaust enough, and lack of backpressure is causing it. What's going on?

 

well, one things for sure... it has NOTHING to do with backpressure. you dont want backpressure.





was the car orignally a manual? or was it a auto and you swapped it to a manual?
if it was a auto, make sure the park/nutural wires to the ECM are NOT connected to each other.. you want the ECM to think its always in gear.
that would possibly explain the stall to a stop...

 

I bet your SES light is on for no VSS. If so then that is why your car is stalling. I had this problem until I hooked up my SGI 5 box.