So im running out of ideas. Im usually the one to help these kind of issues but even im stumped.

When engine is cold i start it up and it stumbles real bad for about 10 seconds and wants to stall and will if i dont touch the throttle. If i start petaling the throttle it finally smooths out then runs great the rest of the day.

today Ive cleaned the :
egr
iac
replaced cap and rotor with brass terminal parts.
past few months :

Fuel pump was replaced with ac delco parts back in January.
fuel filter replaced then too.


Injectors spray fine,but im thinking about rebuilding the throttle body. after 200k miles im sure the regulator is starting to get old. as well as the fuel filters on the injectors.

Timing is advanced 4*,always had no issues with it. i even checked for slack in the timing chain when i had the distributor cap off. Barely any play.

It has no stored codes.
It does have the msd coil. Ive heard about them not lasting long,but If it was a issue with that wouldnt it give me issues throughout the day?

 

I had a bad vacuum leak at idle through the butterfly valve on the throttle body which was causing symptoms just like that. A complete throttle body rebuild fixed it, also found two leaking vacuum lines that were contributing. See if you can rattle the butterfly valve by hand, should ideally be no play at all.