I left work yesterday and was in the parking garage. I turned the car on, let it run for about 20-30 seconds, and put the A/C in the "on" (not "max") position to run it for a few minutes.
Immediately, the idle began what I would call a "surge and settle" cycle. The RPM's would bump up to around 1,750 for about 1 second, then slowly settle back down to the "normal" 900 or so. The idle would rest at about 900 RPM's for 4 or 5 seconds, then bump up to 1,750 again and the whole cycle would repeat.
Once I left the parking garage, and was out driving, I could feel that intermittent surge even while the car was in gear - it was most pronounced when I was coasting in 2nd gear towards a red light - I could feel the car surge forward as the "bump" occurred. 4 or 5 seconds later, I would feel a surge again.
As soon as I turned the A/C off, the problem disappeared.
Anyone have any thoughts? Many thanks in advance for your ideas.
