well when it cold starts it dips at idle and comes back and dips. this repeats until the temp gets up to about 170. once its warm it runs fine, it also luggs whens its cold, thought it was engine electrical but thats all been replaced.

 

done any mods or work to it recently/just prior to noticing this? maybe filled it up with some crappy gas?
i'd wonder if it was getting enough fuel, but seems odd to have problems when its cold to show up in the summer.

 

no serious mods to it other then the exhaust. i didnt notice this on the old 305 that was in it. but now since the 350 has been dropped in and tuned up some it ran great for about a month or two. but now this has started, dunno if it could be the exhaust or maybe a fuel pressure problem.

 

i'm thinkin check fuel first.

goin from a 305 to a tuned up 350 with exhaust work, not enough fuel sounds like a possibility. think i'd try checking fuel pressure and volume test. i have no idea what they should do for volume.

i dont know if this info applies to tbi but i used to have a tpi camaro that ran like crap under heavy load/throttle (bad pump), pressure showed ok, but it'd die as soon as tring a volume test. with a new pump (which fixed the problem) the pressure showed the same, but when testing volume it could fill a 20oz bottle in about 10sec. and not affect how it ran.

as far as "dunno if it could be the exhaust or maybe a fuel pressure problem." maybe if ya got open headers or something similar, but otherwise i think the exhaust would just makes your engine need more fuel

 

simple fix, get a remote starter and warm your truck from your bedroom. I do it, it's great! then you can set your heat or ac and have it just right in there before you even get out there.

 

nah, i was hoping argon would have some input on this one. i made a list of things to check and possibly replace, which are the fuel filter, 02 sensor, tps, map sensor. argon any others i should check out?

 

Just out of experience with putting bigger motors in vehicles, I'd say fuel delivery was your problem. When your motor is cold (especially TBI) it dumps gas like crazy into the motor to keep it running. If you have a tuned up 350, it prob need considerably more gas during warm up. Higher flowing fuel pump maybe? You should notice a difference in performance once it is warm too!

 

yea, checkin fuel pressure would likely be a waste of time, should just shotgun...er replace that faulty o2.

 

yes it has better performance warmed up then cold. dunno what to do about the tbi to get better fuel at warmup and low rpms.

 

maybe an idle motor (Iac valve)...no codes??

also,make sure your tbi gasket is not leaking...listen for any sucking sounds at the base....notorious on those