for the past month or so my car has been running alittle hotter then normal. the temp needle sits alittle higher ( not noticable to anyone but me, it's that little ) and my head feels hotter to the touch. so I'v been keeping my eye on it but the other day I got on it alittle to pass some one...ok I floored it to pass someone and within 3 seconds the needle jumped up like an EGT and then fell down soon as I got off the gas, what could cause engine coolant to spike that quickly?? I have a new thermostat and radiator ( with a little dent from my furry frend ). my radiator cap is super old and the rubber plunger deal thats in it is all decraped and torn, could this minor deal cause the car to do that? my other thought, but this is a long shot, is that my header is so freak'n dented up that the exhaust gas does'nt flow out of the motor fast enough and the temp rises. any ideas?