and most of the O2 sensors out there are "iffy" so I would start by looking there myself.

I reread my post this morning and see that I did not say what I was thinking. Many O2 sensors will pass the test of showing function by fluctuating voltage readings with a VOM. I am told they sometimes get lazy and don't respond quick enough to do a good job. What I meant to say was I would NOT start by looking at the O2 sensor as the root of your problem. I don't see your symptoms as indicating a problem with the O2 sensor. Sorry for any confusion this may have caused.

Not that your symptoms are classic indicators of problems with the fuel injection relay or the RPM sensor but if either are original at the mileage you indicate (not likely) they should be changed. The relay will have a date stamped on the case (it is located on the firewall above the passengers feet).

Randy