ok i know this has been covered b4 but my 2001 ls check engine temp came on while at an idle today once i started moving it went back to normal. i never recieved a reduced engine power or anything else. now to start im going to replace the thermostat. is it in the upper radiator hose like all other cars? is there more than one? and last but not least is there a thread on how to do this that i did not see?