Funny thing, the same thing is happening to me with AC on. But only in the afternoons after work. Runs great in the morning with AC on. But when I get off work ( car parked for 10 hrs) this symptom starts. when I come to a stop, idle drops to 500, jumps up to 1k, back down , then stabilizes . ?
2006 GT Vista Blue . Shaker 500, leather int., interior upgrade. 2x12'' p1 Rockford Fosgates Woofers w/ Kenwood mono 500w sub amp. Pioneer 6x8 225watt rear deck speakers w/ jensen ps250 amp .Bassani Mufflers, X-pipe & high flow cats. Shaker hood , agressive chin spoiler. GT500 Wheels w/ Falken 275/40R18 F/R. Eibach Pro-Kit Spring Kit 1.3" frt , 1.4" rear.