Advice IAC Please help me.

P0505 2002 3.4 auto. I am Super Busy so I had a “trusted” mechanic’s tech clean IAC and throttle body (I did supply both OEM gaskets) and he did phaze (clock)my driveline, It was SHAKING BAD. Running ok when I picked it up.
I drove it 6 miles to home. Started it up the very next day sure as hell it was as horrible running, and the check engine light come on as before I took it to him.
I call and he said it was thoroughly cleaned so it must be a vacuum leak or possibly something else he did clean the MAF.
Hmm, what’s that the best way to find a vacuum leak? Thank all of you for your advice.

 

Have engine running
Start spraying brake clean(the bad chlorinated stuff or another flammable product) over sections of vacuum hoses in engine bay

when you hear engine rev….pinpoint the vacuum hose leak

 

Smoke machine.....anything else is guessing

 

Prob need to give more info for help here. Could be something besides vac leak or IAC. Does it run better at op temp or when you advance throttle?
If IAC is stuck closed it usually will idle bad, stumble etc when below op temp. If IAC stuck open it’ll usually high idle. If EGR is stuck open it’ll can cause rough idle. Again, could be other things wrong. I got no experience on 3.4 though.

 

About half the time above 200K cleaning the IAC wont do it.....

But as THatt told you there is a lot of other things to test/check before you pony up for a new $400 IAC...

And if you are lucky enough to keep the truck long enough......you'll eventually need a new iac

I kept my old one.....but I bet It'll gum up again in 20K or 30K if reused..

and a PIA to get to....


And have to be carefull with these iac's ......install wrong and could throw water down the TB intake