Ok I've had this problem before and I replaced the thermostat water pump and flushed the raidiator. Well I recently let it sit for bout a week got gas and insurance for it so I can get it legal to drive and I found out the starter was bad so I relplaced that and took it for a ride and it overheated again. I let it cool down opened the radiator cap started it up cause I thought the thermostat might have gone out again and it wasn't the thermostat so I need y'all opinion on what the problem could be...

 

need more info.

year
engine

when does it overheat? does it keep climbing when driving? will it over heat at idle? how do you know the t-stat is good? is the fan coming on?

 

It's a 1996 jeep Cherokee 4.0 the tstat is definitely good I started it with the radiator cap open and seen it suck the water through. The temp rises slowly but don't stop rising until it overheats.

 

It overheated last night when I tested the tstat and it idled the whole time never gave it has once

 

Your fan clutch could be shot. When they start to die they won't pull enough air past the radiator to keep it cool, especially at idle.