I had a similar problem. I pulled out the Idle Air Control and cleaned it really well with sensor-safe cleaner spray. THe IAC has a bunch of different names, though... So you may have problems finding the docs for it. If I can, I'll get you a link. In general, it is a small motor about the size of a lime that is stuck into the throttle body. There was quite a bit of carbon on the nose of it, plus some inside the body. Once I cleaned all that out, I never had a problem again.

For what it is worth, I've taken mine to the place on 104th. It isn't cheap, but they seem to be pretty good. They're a little tough to find -- the isuzu sign is tiny. I think their main sign is now a Suzuki dealership.