Idle is varying

i have a 98 jetta wolfsburg 2.0L and when the A/C is running the idle is jumping up and down about 200 rpms difference or so and when the motor is cold it will stall out and die, but once its warmed up it its ok...anyone have any idea's on what is wrong here? I just bought the car and don't know anything about VW cars. Thanks for your help!!

just checked on all the vacuum hoses and they are connected tight, and no breaks or anything, checked all the plug wires and found that the coil wire was hanging off the coil and arcing across so i connected it back and it cleaned up the roughness but the car is still bouncing the idle with the a/c running, but not near as bad as before

I'd try cleaning the throttle body valve.

where is it located??? im VW dumb...used to working on GM cars

i cleaned it...idle is ok but now i have a check engine light, lol, i hate cars!!!!!!

Run by Advanced Auto Parts or Autozone type store to have them read/clear the codes, for free.