Volvo: 1999 S-70 fluctuating Idle, s 70, rpm

Question
I started experiencing a fluctuating idle (550-1000 rpm)with the AC on. The check engine light is also illuminated. If I turn the AC off its not as bad. It does this while driving too. Also, from time to time my S70 will stall when I brake for a stop light. The vehicle will eventually settle down and idle correctly, I am guessing after its warmed up or when I've driven for awhile. Any ideas?

Answer
Pete,
Have the systems codes read. I would say that the ETS system has a fault and needs at the very least a software download to repair that idle. Check with your dealer to see if your car falls under any known repairs with the ETS. Provide the dealer with your VIN.