Well, I was going to post my own, bun since this seems similar to my problem, I'll start here.
My sister has been driving my XJ (Better milage than her '89 Ford F-150 4x4). She was complaining about high idle. But it's always had that problem intermittently. But now it has this deal where it runs rough. Exhaust pops, And sometimes it stalls. Not sure if it's related, but I think it also has a vacuum issue. When I put it in 4 wheel drive and mash the gas, the indicator light goes out. And if I mash hard enough, the axle disconnect will disconnect. I found one broken vacuum line. I fixed it, but the problem persisted. I was wondering where the timing advance is. Doesn't that run off vacuum? Might that cause this issue? Throttle position sensor might also be a good thing to check. What else should I check?
Not sure if this will help anyone, but I FINALLY fixed my JEEP. Turns out the problem was a broken ballast resistor, probably caused by fuel pump & filter issues (which I replaced). The reason my vacuum dropped to nothing, is that since it wasn't getting enough fuel, I'd have to floor it (open the throttle), which makes vacuum go to zero.
Last edited by csmgj
on Fri Jul 22, 2011 5:46 pm, edited 1 time in total.