IAC valve problem??? Can't figure it out, getting fustrated

First off I have a 92 ram 50, 2.4l, 5spd, 61k on it. I will start the truck up and it will idle up and down real obnoxious, so I figured out it was the "idle air control valve" and bought one which cost me $350. Replace the valve, truck ran good for about a week and then one night it started to do it when I was driving. No CEL is on or anything. I'm getting stumped. Can anyone help me out with some idea's? Any input is greatly appreciated!

I also have recently had an idle issue with my 1990 2.4L I had tried everything.... taken off and bench tested the IAC motor and TPS sensors - everything was good. In the end I took it to the shop where they performed a vacuum line smoke test. Turned out I had a badly leaking throttle body. Located a replacement and it runs better, but the truck is now down for a clutch and exhaust system. not to mention the poor idle carboned up my new iridium plugs and brand new O2 sensor that I still have to clean back up before restarting - it should run even better then!

You might want to have a similar vacuum system smoke test run by your local shop - they should only charge about $60-70 (max) for 1 hour labor to diagnose.

BTW - $350 for a IAC motor? Seriously? RockAuto has these for $43, $50 and $96 depending on brand. Where did you go for that thing? Mitsubishi dealer? Did they gold plate it for you? That sounds ridiculously high. Check here next time first, 2nd hand on the forum or in your local yard you should be able to pick one up for between $20 and $30.

Shop smart. Shop S-MART! or just anywhere besides the dealer!

If you ever need a dealer-only part, get the Mitsu stock number and run it through parts.com much MUCH cheaper - if you can wait the 10-14days for shipping.

Lol yeah I thought 350 was ridiculous also but funny thing is I got it from rock auto haha. It's not a motor though it's a idle air control valve. Look it up but yeah idk I'm running out of ideas, only ones I have left is throttle position sensor, MAF, vacuum lines, and ECU? So idk what I'll try next haha