wierd idle problem

[Djayfusion99_es_v6]

ok this is what is happening after hard driving via the free way maybe for about 30mins or so after i get off the off ramp and stop at the light my idle drops to maybe 500 rpms or so and then goes back up to normal rpms. i came back from a very long vacation and didn't drive the car. i did do the service intervals before i left. i have 108K on the odometer currently. can't figure it out. new battery cuz the old one doesn't work forgot to disconnect it before i left. oil change was recent before i took it out. drain and fill trans fluid before i drove it. resurfaced brake rotors. and thats about all i did. any guesses?

[MatrixRenagade]

It only happens after you drive for half an hour? Not on intitial start-up, though? Thats odd.. How old is the gas? And how long did it sit for?

[dknight3]

most galants do that i think. mine does.

[Kwikfox]

Does it keep going back and fourth on the RPM's? Or does it shoot to 500 than go back to normal idle once?

[lonestar22]

if youve disconnected your battery recently then its normal

[Djayfusion99_es_v6]

i know about the battery thing still does it and its only after driving for a while only when i come to a stop but then it stays at normal idle after it drops. It doesn't surge which is throwing me off if it was its and iac prob but who knows maybe it might be an iac problem let me know if u folks have any wild guesses and as for the gas i did put a bottle of stabil and i did put fogging oil in the plugs so my engine doesn't freeze up and my fuel injectors don't get clogged.

[Kwikfox]

It might be your headgasket. When my MR2 was idleing funny it turned out to be the head gasket. However, the first time my mechanic checked, he put some liquid into my engine, and it didnt show any problems with my head gasket. When he took my head off, he found out that my head gasket was damaged, not bad enough to get to the cooling system, but bad enough to screw with my engine. So you might want to check your compression just to be safe.