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We have recently developed an erratic idle and I can?t seem to find the cause although we did find a vacuum pot under the throttle body (that sits directly under the idle adjustment screw) that is NOT connected!?!?! I am unsure of where this would connect, can post pictures if it will help, I can?t find a disconnected vacuum port or a leak although some are capped? I do not think this is the cause as the idle was always stable but now it fluctuates. One minute the idle will be a perfect and smooth 750rpm then it will jump and sometimes stay at 1200rpm, maybe the ECU is trying to make up for the disconnected line. I have checked all connections, timing, and for vacuum leaks, nothing.
I realize there could be a lot of different causes but hope that somebody might have a suggestion on where to start or probably culprits. <img src="/forums/images/graemlins/confused.gif" alt="" />

Thanks for any help.
Bob

you know mine does this also from time to time, 92 3.0L. Im not gonna be much help on this though but if you find a cause, please post.

Which hose are you removing? The large hose directly under the idle adjust screw is from the cold idle air valve, plus there is a small line off the bottom of the dash pot:
- http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml#Dashpot

It is the dash pot that has not been connected. We did not notice it until we started looking for the cause of the erratic idle. I realize this needs to be connected but... Where does the vacume supply come from?? All vacume ports are either in use or capped. Any idea of the results of it being disconnected?

OK so I posted before I read ALL of the text in the link. <img src="/forums/images/graemlins/shiner.gif" alt="" /> So the way I understand it is that the dashpot does not connect to vacume but rather has a check valve and a filter to dampen the closing of the throttle. Where could I find the PN for the filter and check valve and is it realy needed? Could I just run a longer peice of hose and route it to reduce the possibility of contamination or would this cause problems?

As always thanks for the input

Try cleaning out the filter on the end of the hose (if present). If needed a replacement could be obtained at the dealer or at a junkyard.