Idle Surge
 

I have a Volvo XC90 with 105k miles (2004). recently, the vehicle has had a bad idle surge. Literally at a stop sign, the engine will rev up to and down, almost dying. The mechanic replaced the air flow sensor, which helped for a couple of weeks, but now it is as bad as it was before. The mechanic also recommended that the throttle body also get a thorough cleaning, but given the cost I couldnt swing it ($700). Does anyone have any advice on what the problem may be, or experienced the same issue? The error code is p2188. Any help that you can give would be appreciated. Brad

Update. The mechanic replaced the MAF sensor and the engine runs much smoother now. There is still a slight surge that can be felt. The mechanic suggested a throttle body cleaning, but could not gaurentee that this would solve the problem. Since the surge is really small, and the cost to clean the throttle body is approx $500, I declined the cleaning and will drive the car and see if it continues to be a low level problem. Brad