I have 135k on this baby and it just started acting up. So far I did DPFE, EGR, Plugs, wires..just checked the IAC (cleaned and it ohm'd ok). The vehicle still has hiccups when running at slower steady speeds. Vacuum hoses all checked and are ok. It starts cold reliably and runs great at speed and accelerating. I'm getting old and I don't run well but I'm still dependable, guess I'll settle for my ford doing the same. PS.....used the OBD code reader to diagnose the engine lite which led to the aforementioned replacements. The lite is out now, but she still likes to hesitate like an old mule.

 

did you do visual verification of IAC function? Take IAC off of engine intake and leave wire harness plugged in..turn ignition on and off (you dont have to start it) and make sure the piston moves inside the IAC....wont move a lot...just enough to seal the bypass....sometimes they ohm read ok...but get stuck open (or closed) from the carbon buildup on the shaft...

what codes did you get? lean codes? misfire??

might be a small vacuum leak....spray a bunch of carb cleaner around intake areas and see if engine stumbles more (will suck in carb cleaner at any vacuum leak points and will stumble)

my two cents

:-)

 

I always recommend starting with a fuel injector cleaner that you can run in the tank. A cheap way to rule out dirty fuel injectors causing the misfire issue. That and I don't think you'll ever say, "I wish I never put fuel injector cleaner in my tank."

I recommend Sea Foam, but most gas stations have STP, Gumout, etc.