Hello hello
My 1999 3.0 sport 4X4 starts up and idle fine till warmed up .. After warm if I give a little gas rev the idle drops and goes up and down .. Gets so low it almost stalls then up again and down .. Does this in park and neutral but when I drive and come to a stop it stalls or if I slow to turn it will die and I lose all pwr stearing . there was a lose idle adjust screw that manual says is factory set so I basically turned it in by finger until lock nut seated .. Would that cause a loping ? .. I would think it would just stall from super low idle not rev up and down .. Vacuum lines are all solid .

Any ideas?

 

Try removing the battery cables for a short time and then reconnect (Of course, you may lose radio presets.) That should reset the computer and force the car to "relearn" the idle. Drive it for a while with AC on and off at times and things will smooth out - hopefully!

 

It sounds like a vacuum leak. You said the vacuum lines are OK. Check them again. Also, check the manifold boot for any cracks or bad connection. To eliminate vacuum leak you can start the engine and while its running, spray starter fluid in different areas after the MAF sensor (the boot, throttle body, vacuum lines). Another possible cause is a sticking/not working EGR valve.

 

Thanks
Seems the computer really knows what its doing .. And some helpful hints from the friends on the forum the engine idle is smooth and happy .