i'm running at highway speeds (75-80) and the weather is on the warm side, the check engine light will pop on once in a while, if i drop my speed back to 55 or 60, it turns back off again. i have good, clean oil, a new filter, i change trans fluid and canister filter every 20,000 miles or so it has a new o2 sensor, new plugs and wires and the egr only has about 40,000 miles on it as well. the car isnt over heating and this happens whether the a/c is on or off. where should i start looking next?

 

read codes and post

 

what kind of plugs are you running-sounds like you might have a misfire going on but like derf said if you can find out what codes are being thrown

 

just the good ol' ngk copper plugs, same ones this car has had since it had 4 miles on it. i'll cgeck the codes in the morning.