HELP, a newbie here and my car is about to send me over the deepend. I have a 1993 323 1.6 manual base model. In the past month I have had a major tuneup, new dist cap, dist rotor(actually 3rd one in 2yrs), plug wire set & plugs, pcv valve and a valve cover gasket. The car is having a random problem of quickly cutting out while driving which makes the car jerk and the revs go crazy when idling. But this only happens when the car is warm and some days it doesn't happen at all, runs great. Sometimes it will occur for part of my drive then run fine the rest of the way. A mechanic diagnosed it as a faulty "Air bypass valve", but I can't seem to find any info on such a part.. He tells me it is the valve that keeps the revs up when starting the car?? I am also told that the part can only be purchased through Mazda at a price of $700 CAD and they couldn't find a used one. They couldn't give me a part number and the Mazda dealer has no idea what it is. Am I getting ripped off or is there such a part under a different name, and is this really even the problem?

ETA- Nevermind, after searching deep into the forums I found the proper part name 'Idle Air Control Valve' and yes it's around $700 new. Luckily I found a used throttle body for $100.