I was wheeling on Saturday & noticed all of a sudden the Jeep was running differently. Sitting with it in park it idles fine & revs fine. On the trail, in drive, it stumbles/shutters. It does a very small amount in reverse too or it could just be my imagination.
When my wife & I noticed it I immediately got out & checked the exhaust system. Felt like it was flattened. Everything was fine. I then checked to make sure there wasn't a hole in the transmission pan. Thought it might have been loosing fluid. Nope.
We weren't too far from a town so I figured it would make it to a parts store & look it over.
From a stop, it would accelerate but like it had a bad plug or wire, transmission slipping &/or vacuum leak. Once it shifted out of 1st gear the issue went away. One time it did it in second also. That, or it never shifted from 1st. Not sure.
I figured that as long as we maintained highway speed we'd be fine. So we hit the road & didn't have any problems until we stopped for food. But once back on the interstate, it was smooth sailing.
We made it home just fine. Since then I've
- added a pint of ATF
- pulled each spark plug one at a time while running
- pulled the air filter
- checked for vacuum leaks
- checked fuel pressure (31 & 39 with vacuum line off)
- cleaned the throttle body & IAC
- replaced throttle body with a spare that contained it own tps, IAC & whatever else was on it
- replaced the fuel filter
None of the above had any affect on the issue.
What am I missing?
It's a 89 I6, automatic with a bone stock engine & 25x,xxx miles.
I did plugs, wires, cap & rotor button about 5k miles ago.