When the car is cold and I go to start it the car fires up for a few seconds then dies. I can do this a few times. I can feather the peddle and get it to idle but its really ruff and misses bad when I'm giving it gas like its getting too much fuel. Once it warms up a little bit it runs great and starts great. I have no clue what can be cuasing this. 91 lx 5.0, aod-t5 swap, f cam, 24# injectors and maf, billet regulator, custom aluminom intake, edlebrock tb, cold air intake, bbk full length headers, 255lph pump

 

I have tried two differant IAC motors.

 

engine coolant temp sensor possibly going bad.

 

put a new temp sensor on it but not any better. I picked up a can of maf cleaner while I was there. Maybe that will help?

 

KOER TEST would of determined bad ect, just because the prob is more evident in open loop DOES NOT mean automatically it's a bad ect, open loop strategy is based on a few more inputs than just ect. Run a koer test, check for codes and if none exist, make sure base idle has been properly set , then look for vaccum leaks, however if a vaccum leak is present and base idle has been adjusted to compensate for such, it'll throw the system out of wack