1995 Buick Century engine surges in park

My car has been doing this for at least a year now and I have yet to find an answer. My car drives great for the most part. It accelerates nice, trans shifts smooth, for the most part. My problem used to be intermittant. When I would drive it up to my house and put it in park it would surge, sometimes feel like it was about to die. It usually levels off after about a minute or 2. Now, the problem happens all the time. The problem even happens first thing in the morning when I start my car now, it will surge, but the second I put it into gear it runs alright. It hesitates a little for the first block, but I think maybe the surging gave it too much gas. It's got 1 new injector, new egr, new delco wires and new plugs, pcv, vacuum hoses, fuel filter, and alternator. Please help me. I love my car.