my car idiels @ 3000 rpm when I start my car up, as it warms up after driving for 3-5 mins it drops to 1500 rpm. during that period when I start my car, my engine idiels up and down from 3000 to 1500 rpm for the time it is warming up. If u noe whats wrong or what I need to do, or possible problems please let me noe, thx B16A owner

 

replace your ICV (idle control valve) its bolted on the manifold next to the throttle body on the back

 

could be a bad IAC valve as well