i took my radiator out (as described in chilton's) to check for leaks since i was refilling my coolant about every 2 weeks. installed radiator again after seeing i couldn't fix it. put some alumiseal in, but didn't have enough coolant to fill radiator. Put what i had in, not very much, hoping it would pull coolant from the reservoir (yes i am new to cars). drove the car afterward for about a mile on my way to buying more coolant before i stopped because i heard a rattle. then drove another 1/2 mile before it completely shut down on me. no smoke from exhaust, no warning lights, nothing. opened the hood and a little smoke coming from left side of engine which stopped after a few minutes. Got some coolant and filled the radiator. engine sounds fine now, but once i am in 3,4,5 gear(automatic), rpms don't go up as high as before, loss of power going up hills. oil not milky and its not overheating(temp staying in normal range). have driven it now about 30miles after refilling radiator. someone told me it might a cracked or warped head gasket. any advice, thoughts? could i replace the head gasket myself?

If the oil is not milky and you are not over heating then I'd say your head gasket is OK. Sounds like you may have got an air pocket in your cooling system after you replaced the radiator and it got a little hot. The cooling system will draw water from the reservoir but I think it does so when it cools and draws a vacuum. There is a test that radiator shops can do. I forgot what it's called but I've done them before. The test detects carbon monoxide gas in the coolant indicating a bad head gasket or cracked head. I can't figure out the loss of power. Got me stumped on that. :confused: