I've been having a stumbling problem lately (not alcohol induced either lol)

I thought it was the TPS so I had it checked and it was bad (I had a feeling it was cuz I had a problem with mty truck idling up and down sometimes) so i had it changed, but the problem is still there so i had the fuel filter changed and I cleaned out the IAC.

Seemed fine at first but its still doing it, and its really starting to **** me off.

I thought at first it would stumble when I would touch the gas but I have just figured out today that it stumbles as soon as I get off the brake and havent even touched the gas yet, which seems pretty weird to me.

Thanks in advance for any input.

 

oops, sorry I forgot to post what kind of vehicle:

87 F-150 5.0 Auto EFI

 

No ideas?


Anybody think this could be caused by a bad EGR valve or oxygen sensor?

 

I doubt that the EGR would be a problem as it would normally not be able to idle if that is the problem. I would check for vacuum leaks.

 

Cant find any vaccum leaks at all, checked all hoses, unless the brake booster itself is leaking?

I thought i heard somewhere that unplugging the IAC connector with the engine running and the engine dies means the IAC is bad, is this true?

Thanx