16 v runs very different with a/c on
 

here's my situation : the car runs fine at idle with the a/c on(small
pulses like some correction taking place but remains fairly steady @ 900 rpm).however once the a/c is off the temp creeps up to @110 and the idle goes haywire,revs to 2600-3000 & stays there.

only way to bring the idle back down is to turn the a/c on & wait for the temp to drop or turn the car off.am I fighting more than one problem?please help!!

1986 190E 2.3-16