There is no such thing as a "mass airflow bypass valve/solenoid". I think that was someone just making up some name, because they really had no idea what it was called.
Heck, the truck doesn't even have a mass airflow sensor! lol
The IAB is either open or closed, nothing inbetween. It doesn't even constantly stay open. The EEC sends pulses that makes the IAB flutter at a very, very high speed. The fluttering does occur during the duty cycle.
The IAB opens for starting the engine, idling the engine, deceleration, and WOT. It's there to prevent the engine from stalling when the throttle body closes. It's open at WOT so incase you quickly let off the throttle, it's already open and your engine won't stall.
Have you checked for error codes yet?
Try unplugging your IAB and see if the idle quality changes. If it starts to stumble or even stalls, the electrical part of the IAB is working. If the idle doesn't change, something is probably wrong with the electrical part of it.
Last edited by Speed_Demon1965; 01-05-2005 at 10:21 PM.