What broke?

Took the jeep over to get my boat out yesterday, the ramp is steep& muddy so I had to use 4hi to get out. I had the E-brake on to get the rpm's up so I took it off when I started rolling forwards.

On the way home I noticed that it was driving like an automatic because it was accelerating by itself& red-lining when shifting even though my foot wasn't on the pedal. I stopped to restart a couple of times, that didn't work so I shifted into neutral, floored it really quick& that fixed it.

I know that this doesn't have cruise control so what broke?

It's a 1990 Cherokee Pioneer w/a 4.0& a 5spd

Check that you didn't lose the return spring on the throttle cable.

Several things can do this, all of which I've experienced at some point or other on an 87. There's the throttle return spring, already mentioned. The throttle linkage bell crank on the side of the manifold can wear and stick, and the gas pedal itself can start to bind. You might also have a dirty idle air controller or a bad throttle position sensor, but since it responded the way it did, I suspect the linkage somewhere. ON the 87, when the bell crank got really bad (just before my daughter was to sell it very cheaply anyway), I was unable to get the bolts off to replace it, so I just added a spring to the linkage at the throttle body, to help pull it closed.

Took it on a 100+ mile road trip today& it acted up again, this time I knew how to make it stop.

Thanks for the help, I'll be looking into everything mentioned here

MY '90 XJ 4.0 AW4 was doing the same thing, bellcrank seemed real stiff, tried to get another ,ya right....so lubricated the heck out of it...still did it once in awhile, so I replaced the throttle cable...still had same prob., then one day I couldn't get it to kick down when it started "racing"...replaced TPS...been fine ever since......good luck with yours.

Could be the IAC valve, mine gets stuck from time to time and my rig idles at 2500-3500 rpm's, I can just put it in gear and let go of the clutch and it goes by itself. Usually all I have to do is tap on the IAC on the throttle body and all is fine.

Don't mean to sound stupid but what's the IAC Valve& what's TPS? I'm new to XJ's

Thanks for the help guys