Hello, sounds like your a/c was not working for awhile.I think 2 conditions
are occuring here. First, with your compressor now charged up, it has a
load on the engine. You can actually feel this when the a/c is switched
on.This brings the second point up.this drag is compensater for with a idle
compensater switch.It raises the rpmof the engine the ammount that the a/c
brings it down.I think this switch is not working. When thea/c turned on
your rpm'sdown to a point where the engine doesnt want to accelerate. Also
your ignition timing may be off a bit.This switch is located in the front
right of the engine comartment. It has a companion switch next ot it for
the power steering. They look the same.The electrical plug may be
disconected, or the vacuum hose felloff.Other stuff can cause this too, but
try these first.