97 Cherokee Issues

I have a 97 Jeep Cherokee Sport that i purchased last year with 140,000 miles and it runs great. There are a few things that bother me though. First, whenever I put torque on the motor, like when i am going up a hill, i start to hear a knock in the engine. Does anyone know what the knocking could be and is there anything that i could do to get it to stop? Every once in awhile my check gauges light flashes and shows that is is overheating. I let the jeep idle for a little bit and in a matter of 10 seconds it goes from red down to just a little above the normal temp. Could this be the thermostat or a temp sending unit? Any input is appreciated. Thanks

The noise could be

Loose torque converter bolts or a cracked exhaust manifold

for the over heating check to make sure your secondary fan is kicking on, ( it will turn on when the ac is on and when it get s hot), check to make sure the fins on your radiator are in good shape and not plugged with leaves and bugs (make sure they are still there, the fins), and a t stat is an easy job to do and its cheap....

Good luck