I have a 93 NA Supra and it just refuses to idle the way it should, it either idles way too high ie 1000 - 1100 rpm, or way too low ie 400 rpm and i have to turn on the damn air con to compensate for it. ive had the throttle body & air filter both cleaned out... what the hell could be the cause of this??? could it be because i have a HKS aftermarket air filter?? weird thing is if i turn the car off and back on again the idle goes back to where it should be.... fck'd up!!

plz help im so frustrated!!