I would certainly never disagree with a tune up for any car that hasn't had one lately, so that is a consideration. If you are in need of a good tune up, certainly do that first. After tune up you can choose to drive it for three trips to see if the MIL turns off or you can clear the DTC and take two consecutive trips, after which the MIL will relight if problem is not resolved.
If you have recently done a tune up and are sure of the results, then inspect the wiring harness and connector to the EGR Valve, first. Check the connector and pull it off and push it on a few times to loosen any corrosion, then use some dielectric grease on it before assembling it the last time. Check for worn or loose spots in the wiring.
If all'* well with the wiring and connector, then pull the EGR and look at the pintle to make sure there isn't a carbon build up. It can be cleaned.
Let us know what you find.
Mike: 1997 SE w/ 183K, aka White Horse
, Gutted Airbox w/K&N, drilled 180* t-stat, tint all around, clear corners w/SilverStars, "PONTIAC" light up tail, PEMs, NGK TR55s