DuramaxJut

Was told it has a new fuel pump. I replaced the fuel pressure regulator, replaced the idle air control valve. Adjusted the throttle position sensor. New starter. Run nothing but 93 octane. What else can it be? Cranks and cranks for about a minute then fires up. Then it's fine all day except at a light in drive the idle starts jumping around. Thoughts?

Bob88GTA

iTrader: (2)

If you changed the IAC, it would be a good idea to follow this procedure to a T.
https://www.thirdgen.org/newdesign/tech/tpimod2.shtml

Also, what year,engine,TPI,TBI....what. What is your fuel pressure at idle? Cold Start Injector Switch and Coolant Temp Switch could play a role in this. Does it start when warm?

ATM, to many variables

DuramaxJut

Thank you. I will have to try it. It's an 87 with the TPI 350. Cold start switch and coolant temp switch I have not changed yet. It starts right up once it's warm. Only have troubles after sitting over night. I have not checked fuel pressure yet.

DuramaxJut

UPDATE: changed the coolant temp sensor today after the CEL came on for the sensor. Didn't change the the pig tail but it still seems to idle weird. Couldn't find anything about a cold start switch online and I'm sure it'll have the starting issue tomorrow morning.