99 GM surges only when heat or a/c is on, ideas?
Had the car about 6 months, 140K. miles. Just as the title says, I turn on the heat and it surges when coming to a stop or sitting at a light etc. It runs fine at cruising speeds. Can someone point me in the right direction? I don't like throwing darts blindfolded. Thanks in advance, Mike.
(I tried searching but no luck.)