When I'm driving, with the A/C on, the engine surges big time, it sucks to drive with the a/c on, but I live in FL and need it. A/C blows cold air, but when the surge occurs, I hear a vent/duct slamming shut under the dash. Also, when at idle, the a/c cyles, and the idle jumps up and down every min. or so. Did a search, didn't come up with anything solid. Saw it might be IAC or an A/C pressure sensor.... Anybody seen this before? I could just start shot-gunning parts, but hate to replace an IAC or anything else for that matter, when I don't have to.