I just changed my jeeps detent/kickdown/ av cable bc it was shifting rough and wouldn’t go over 35 flooring it unless I dropped it into 3rd. It still shifts rough but it gets to 45 and stops unless I drop into 3rd. While changing the cable it pulled out another line coming off of the transfer case for the front diff and I can’t figure out where it goes bc I don’t want to drop everything out of it. Now my f-ing temp gauge bounces up whenever I hit the gas. Thanks in advance for any help you guys can provide bc it’s more than I’ve got now

 

The temp sender wire is at the driver's side back of the head. Does it have a bare spot that touches ground when the engine moves on acceleration?

 

"line coming off of the transfer case for the front diff"

So 1990 is still has the vacuum operated disconnect for the front axle. One is vacuum supply and the other goes over to the passenger side up near the lower control arm mount and then down to the axle. Sure you're not looking at a vent line that doesn't get connected to anything? There is a vent line for the front diff that runs up the control arm into the engine bay. Usually some sort of vent cap or u-turn fitting at the end so it get get water in it but often that's missing.

It sounds like you have a power problem rather than a shifting problem. Check the wiring to the temp sensor as Cruiser mentioned. I'm also willing to bet your motor mounts are shot.