The IAC was replaced, and the problem is worse.

[BrooklynBay]

Thanks for the update!

 

[2002GreyHD150]

I had similar problems & same Troubleshooting pattern... couldn't get it... got to the point the truck would Die on deceleration on the highway....

I got this solution from a TSB I found online. '02-'03's had more trouble with the PCV elbows & lines tearing, cracking, disintegrating & the IAC. So its important to note the differences between the 02-03 4.6L Cable Drive versus the Drive-by-wire of the '04-up.

Remember, starting in '04 some have an EGR & some have an IAC., some don't. My wife's '04 4.6L, AWD Monty has Neither. Drive-by-Wire makes it even more trouble, as you cannot find replacement TB's if the solenoid goes out, you don't replace the solenoid, you replace the entire TB. Cool $700 from the Stealer... I mean Dealer.

Removed the intake hose, sprayed TB/Carb cleaner on a towel, wiped as far into the TB as I could get, problem totally solved!

Stopped @ Autozone on the way home,got the new TB gasket, as it is NOT a rubber reusable one like the elbow to manifold or manifold to heads... Used the CRC Throttle Body/MAF/Carb cleaner cleaned it off the truck. Completely. Scrubbed the interior with a green scotch brite pad till it gleamed. Went ahead & cleaned the MAF (integrated into the Air filter Box starting in '04) & cleaned my K&N filter for good measure.

Now we have picked up 2mpg, truck runs better, pulls harder, runs quieter. Amazing what 150K of oil residue can do to the IAC/EGR/TB circuit.

This weekend, finish it all up, fix the damn oil filter adapter leaking gasket, fuel filter, fresh plugs, Driver's side new bearing/hub/abs sensor, New tires...It been a "fun" & expensive month for the Monty... but 170K & if that's all I ahve to fight... its paid for I am happy.

Rob

 

[SyberTiger]

That didn't work. But I did unplug the IAC and started it up. The idle was low but consistant. Does anyone know if that is telling me I might have a bad IAC? FYI-it is a brand new IAC installed.

camcam, what was the solution to your problem? I also would like to know what it means if you unplug the IAC and the idle become consistent. I've tried three BWD made IACs that I got from Advanced Auto and everytime I get a different result with them. However, I still have idle problems. I know I need to get a Motocraft IAC but for now I'm having a hard time thinking three BWD IACs are all bad out of the box.