About ever second or third time I either start my car or come to a stop the idle will fluctuate between about 500rpm and 1000rpm four or five times before settling. The other times it settles in like it should. My boost gauge reads 18 inches of vacuum at idle consistently , but I'm gonna check all the hoses to be 100% sure it isn't vaccuum related. Has anyone else exerience a similar issue? If so what fixed it?