problem, stereo, 92 jeep cherokee

I have a 1992 Jeep Cherokee that i have recently bought. The Stereo in it has not worked properly since i bought it. It works but only turns on when it wants to and does it by itself. Then it's only on for a little while before it turns itself back off. I'm out of ideas as to what could be causing this. Please help me.1992 Jeep XJ - Dana 35 rear

               Dana 30 front

               4.0L I6

               245/75/R15

Several different things can cause this. What all have you checked?

is it the factory radio or is it an aftermarket? if its aftermarket then what brand is it?

I would see if you can check power on your constant and ignition wires going to the stereo when it does not want to come on. Testing both back to your ground wire. I would say its the deck if you get 12V on both. Sometimes they just get old and crap out. If you have a shotty connection it could also be causing this. Do you lose all your radio presets everytime it comes back on? If not then I would target the ignition wire more. If you do then I would target the constant or ground wire.