Have not received any replies but I thought I would update my problems in a little more detail. Except at idle, the car performs great. Gas mileage seems to be the same as always. The car has 65,000 miles, had the car since new. The idle problem is intermittent. At times, no problems, at other times, surging to 1000 rpm and then back to 500 rpm within a few seconds and repeating. It seems that having even a small load (such as having the transmission in "D") takes away most if not all of the idle problems.
There also seems to be a new symptom--sometimes, but not often, when trying to start the engine, you can grind on the starter for seconds with nothing firing at all. Even though the car is turning over, even the tach does not register any rpms. Ten seconds later, it starts immediately.
I would appreciate any help or tips. I plan to take the car to a pro next week but just wanted to understand what my problems and/or options might be.