any advise on a stumbling idle after the engine warms up? I can reproduce this at will. engine starts fine and is okuntil it starts to warm up and then gets progressively worse with temp until it is virtually stalling and then bumping back to idle with associated vibration as though it's missing. happens everytime, and then may be difficult to restart if warmed up and restarted. i have cleaned the idle valve out, cleaned all electrical connections (coil, accelswitch,etc) and replaced a couple of suspect vacumn lines...still the same..02 sensor maybe? or could the idle control valve be shot? i hope not, those things are expensive but easy to replace...any back yard mechanic way to verify that the valve is functioning? thanks