flaky car

[MasterMan]

alright i dont know what the hell is wrong with my POS.. today i got gas, went home (every thing runing nice and slow as normal) i pick my bro up and we drive about 3 miles.. i stop at the bank and just had the car in park.. then it drops from 700RPM to 100- RPM then bounces back up to 1k RPM.. and would just keep doing this, almost dieing but it would bouce back b4 it would kill.. then i would give it gas and it would stop.. then we go to buy cigs at 7-11.. sits there for a good 3 mins then starts doing it, but this time the engine check light comes on... go back to my house and let it sit.. about an hour later i got to school egine check light still on.. im riding down wickham and the light turns off.. now its back to normal!! only thing is this happenes about ever month.. just changed the oil about 2k miles ago.. everything seems fine.. anyone have any ideas? idle controle? O2 sensor? hmmm

[Nismo_Freak]

IAC Valve... also check for possible vacuum leaks.

[MasterMan]

alright thanks man