[200TQ]

hey guys. i love my car but its giving me a few problems. when i stop for a stop light/sign etc., my idle becomes very unsteady, rising and dropping very fast,(between 1500 to 1700rpm). it does this every time i drive. usually at every stop. every once in a while, it will smooth out and drop to a slightly-higher-than-normal idle. i unplugged the idle control valve when it was running unsteady, and the idle dropped and stayed normal, even when i plugged it back in. this is a used valve. i replaced my old one b/c it was doing the same thing. should i get a new valve? or does someone now that its something different?

 

[urq20v]

Have you tried cleaning the ISV?Give it a good clean in a container of petrol and make sure all the gunk buildup is cleaned out and the rotating valve inside moves freely.
Air leaks could also be a problem.Injector seals,ruptured hoses etc.Check that the crankcase breather from the left side of the engine going to the rubber junction hose on top of the cam cover is not perished.These can look fine but in fact are like jelly.They invariable have a split in them when perished.Generally check all vacuum/boost hoses for splits.

 

[200TQ]

thanks for the input. i did clean out the isv a couple of times and found no perished hoses. but lets just say that it is an air leak: wouldnt it still be an air leak even after i unplug the isv? like i said before, while the engine idle is unsteady, i unplug the idle stablizer valve, and then plug back in, and the idle drops to normal. i think that if it were due to a leaky hose, the idle would be unsteady even after i plug it back in, right? also, if i stomp on the gas while the engine is cold, it will hesitate really bad. it starts going normal, and then suddenly.....nothing. feels as though the w/g opens. any ideas?thanks!