Hi everyone,
Just to let everyone know I have read the post on the rough idle...

The few problems we've been having with our 1997 Olds Cutlass Supreme (v6 3.1) seems to be an intermittent idle problem.
The first one we noticed while sitting at traffic lights, or in a parking lot the car wouldn't idle smoothly as in it fluctuates a bit, a rough figure maybe 100rpm.... also when it does this the engine seems to run a little rough also enough to send vibrations throughout the car. This problem happens on and off, it never seems to be consistent. Sometimes pressing on the gas a little while in park helps cure it for a bit, but it still comes and goes at random times. This problem seems to have plaguing the car for over a year. Then my bro changed the PCV valve, changed the plugs...

The second problem which I've noticed just a few days ago, after starting the car and putting it in reverse the revs drop and go back up... another rough figure would be 300rpm to 1400 rpm.... Also when it does this it seems like the car will almost shut off but then it kicks the rpm back up again.
Then I put it in drive and the problem still carries on but eventually disappears. Once again this has happened twice and seems to be an intermittent problem also... who knows if it will happen again.

My bro and I have ran the OBDII Automotive Diagnostics program while driving around in the car and checking the O2 sensors. So far it looked okay... but a year or two back one of my bro's friends who has a more advanced software for OBII said that the O2 sensor a bit out of it.
We think the original O2 sensor is still in.
So far we haven't got any engine codes, but once we got one for the EGR valve but that was once, around a few months ago and never came again. We do regular maintenance on the car and everything else seems okay.
As I looked on the net for this idle problem and some people have succeeded in changing the EGR gasket and cleaning the valve itself, but if I'm not mistaken the EGR valve on this Olds is a digital one, would this help at all? The hose under the EGR valve should be tight or not?

thanks for any help,
Raj