When my truck idles it will randomly surge forward a little. I searched and it looks like most likely a vacuum leak. Well I sprayed carb cleaner around the carb and the idle never changed. I just put headers on not that long ago, so could that have something to do with some of the smog crap no longer hooked up? And I changed the plug wires and I might have switched the lengths of a couple . Could that do it? Anything else?