So the car in question is not mine but my brothers, anyway, his car has been giving him idle problems, it will run like a swiss watch without the A/C on and will run just as great will driving down the road but as soon as you come to a red light and the car idles down (again with A/C on) it will idle at 700 RPM then have sudden surges where it drops to 500-400 and then comes back up for about 30-60 seconds then drops again, i've noticed that the A/C compressor kicks on when the surge happens...

Idle problems (can't figure it out)