1989 Questions for all other cars engine idle

my car is a 1989 mercury merkur xr4ti manuel shift the problem im having is that the car idles normal but then it the idle rises up to two thousand rpm for a few moments then it gose back to normal idle. i have noticed that the timing marks move when the idle rpm rises. is this a normal system routine. will this affect the cars ability to pass a smog test assuming everything else is is opperating right