Ford: engine surging, oxygen sensors, vacuum problem

Question
I have a 1993 Ford Taurus 3.0L V-6, automatic. Just recently the engine has started surging while running & in Park. When I put the car in gear, the surging stops, but gas mileage is also bad. The surging is noticeable for a while, but it can be intermittent at times. I don't feel that it is a vacuum problem as it is intermittent.

Answer
the rolling or hunting idle could be your IAC Idle Air Controller giving your problem there. As for the gas mileage concern I recommend a tune up first, then possibly having your oxygen sensors checked. the sensors could be fouled up from age and may need to be replaced. See if the surging happens with the heater in the off position as well. If that is the case disconnect the battery for 10 minutes and retry it. Let me know how you make out.

Jim