Nissan Repair: high idle speed, correct screw, air screw

Question
I HAVE AN 88 PATHFINDER W/150,000 MILES AND V6 ENGINE AND 4WD. THE IDLE SPEED IS HIGH. WITH ENG. HOT THE IDLE SPEED IS ABOUT 950 RPM. I TRYED TO ADJUST THE IDLE SPEED SCREW BUT THE SPEED DOESN'T CHANGE NO MATTER WHAT DIRECTION I TURN THE SCREW. ACCORDING TO MY HANES MANUAL I'M TURNING THE CORRECT SCREW. AM I DOING SOMETHING WRONG? DOES THE CAR NEED TO BE IN DRIVE WHEN MAKING ADJUSTMENTS? IS THERE AN ELECT. CONNECTOR THAT I NEED TO UNPLUG BEFORE MAKING ADJUSTMENTS SO THE IDLE SCREW WILL WORK WHEN I TURN IT? I WOULD LIKE TO DECREASE THE SPEED TO ABOUT WHAT IT SHOULD BE, 750 RPM. WHAT DO YOU THINK IS MY PROBLEM? THANKS VON FOR YOUR HELP IN ADVANCE.

Answer
Hal,

I would check for a vacuum line that is disconnected first.  But, there is a minimum air setting that you need to adjust.  I would put the idle screw back where it was and go for the minimum air screw.  Check the Haynes manual for that procedure.  But, I would almost bet you have unmetered air getting in somewhere else like a bad vacuum hose or a gasket.  Email me back with what you find.