High Idle...strange

[boogie94xj]

Occasionally my 88 MJ will have a high idle almost like it has a vaccum leak somewhere. Sometimes a quick tap on the throttle makes it go away and other times it doesn't. The truck started doing this after installing a bored out TB. I put the old one back on and the problem went away but has recently returned making me believe it has nothing to do with the TB. I sprayed around both TB's with WD-40 looking for the leak but nothing seemed to work. Could it be a sticky IAC motor?

 

[old_man]

Blipping the throttle should have nothing to do with the IAC. My XJ started that on a trail run at Moab last year, but quit. It seems to be a fairly common problem, but I have yet to see a definative answer to its cause. I think at Moab, it may have simply been grit in the throttle shaft. When I got home it was pretty dirty and I hit it with carb cleaner. My rig is a trailer queen so it does not get that many miles any more.