i have a 1990 cavalier z24 with a 3.1 engine and 5 speed tranny. my engine temp it usually around 200 degrees. that sounds a little high to me. should i flush the cooling system and replace the thermostat? also my oil pressure gauge is maxed out. the only time it drops is when i'm taking off in first and i bog down the engine enough alsmot stalling it. when downshifting to come to a stop and the revs go up just under 3 grand i get a backfiring spiting sounds out of the exhaust. it doesn't sound very good and i'm wondering if it's a major problem or not. i bought this car 3 months ago and have only filled the tires with air, changed the oil and filter, and cleaned all 4 brakes and replaced the front pads, so other than that i haven't checked anything on the car.