I have a 1987 Jeep Cherokee Pioneer made by AMC, it's an automatic.
It was running perfectly fine until after a night of letting it sit, the next day I took it out and wouldn't shift out of first gear. First thing that came to mind was my throttle position sensor, so I ordered one online and replaced it.
It helped, but still didn't completely fix the problem. After it hits 2500rpm it shifts into 2nd and after that, perfectly shifts through the rest of the gears. It's never done this before. It usually stays under 2000 rpm.
I'd like to have someone's input on this? Any suggestions? Any help is greatly appreciated.
Also do you think it would be okay to drive it around like this? What about with a cargo trailer weighing around 2000 lbs?

 

What condition is the fluid in? Correct level?

 

Give this a go in the mean time: https://www.cherokeeforum.com/f2/free-quick-fix-41821/

However, unless the cable mysteriously snapped, that won't cause sudden issues like you describe. Fluid leak or blown TCU fuse would, though.

This has the 4.0L or 2.5L engine?

 

Elena, click on the link below for some helpful tips in finding "gremlins".

I would advise 1 through 4 to begin with but take a look at Post 10.

Did you adjust the new TPS?

 

Myself, I think I'd at least hold off towing the trailer until I had it sorted out. I'd be doubly sad if it not only "died", but I helped kill it as well.

 

My '87 Pioneer did something similar to this. People on this forum suggested cleaning the throttle body and TPS with Seafoam cleaner.

It worked. Mechanic guys said there was a lot of carbon in there. Doesn't run away with me anymore.