MDC9966

After the car set's overnight or even all day at work, it starts rough. I alway get in turn the key on, wait about 5 seconds or so to make sure the fuel pump has done it's thing. I turn the motor over, it cranks and starts imediately. It then idles very rough almost dieing. If I let it run its course it will eventually even out and idle correctly but it takes about minute or so to clear up. If I just turn the car off and restart it then it always idles fine without the minute waiting period. It has a new fuel pump, fuel filter, air cleaner and plugs. It did this before I changed those and never improved. I don't think it's the injectors because once it warms up you couldn't ask it to start and idle any better.
Could it be the IAC or the throttle body?
Thanks

JonM

Could be those, could be a bad O2, bad egr Solenoid or valve. Could be anyone of these things. Time to get the volt/ohms meter out and play detective. Getting any codes?

MDC9966

No codes, new egr, solenoid, sensor. ECM check show EGR working properly voltage wise. What should I look for in the 02? Wouldn't that cause it to run badly all the time? It only shutters and shakes during the first start up after setting at least 8-12 hours. It is parked in my garage at night so I don't think moisture is the cause. What voltage readings should I be looking for? I'll have to check them quickly in the morning or it will never show up.
Thanks,

Mike263

If it does it only when cold, it's not the O2 sensor. You haven't gone closed loop yet. O2 is only used when the ECM goes closed loop.

Wish I could offer more.