I have a 97 Jeep Cherokee Laredo 4X4 it has the 42RE transmission ... problem its popping out of gear & making a grinding noise. I have replaced the governor sensor & solenoid ... when I changed them

Sounds like the screen in the valve body or the governor screen is getting plugged up with debris every time you drop the pan to replace the solenoid. Everytime you replace the solenoid for tge governor it has a new screen that isn't clogged. This is a sure sign you have friction disks that are on their way out. Probably in the direct drive clutch pack. You have a forward and direct drive clutch pack inside your transmission. Plus an overdrive clutch pack, and a lo/reverse band and a kick down band. The friction materials are failing. Yes you have a primary filter, but it doesn't catch everything. Once the small particles get into the valve body the problems start to appear. My guess is time for a teardown and rebuild. Let me guess. Your way in excess of 150,000 miles. Hope this helps. Not good news though.

Sounds about right... I take it the 4wd low is on a different system?... because it works no matter what.