Since you say you just rebuilt it, I would check the gaskets for starters, check the EGR valve and gaskets since you probably took that off, and most importantly make sure everything is tight.
To check for vaccum/gasket leak take a can of carb cleaner or starting fluid and slowly spray each gasket, metal metal mating surfaces and vaccum lines, if idle changes you found a leak.
Maybe you have a faulty IAC module.
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Sunday, February 3rd, 2008 AT 6:43 PM