'91 Grand Am start problem

1991 Grand Am 2.5L engine 150, xxx miles. I have had this car for over a year for a work car and drive it daily about 60 miles. It has had a jerking feeling at mid range speed (25-40) since I bought it, ran smooth at 55-60 and accelerated fine. It never got any worse so I lived with it. Now I have another problem ( may be related or not ) The last 2 weeks it has cranked a little longer in the mornings before starting, 10-15 revs as opposed to 3-5 before. Had no problems while running and started good in the afternoon. This morning it just cranked and cranked but never hit a lick. Did not even attempt to start. This past weekend I replaced plugs and fuel filter, did not help. It has a new battery and starter about 6 months old. It was to dark to check out this morning but I would like a place to start when I get home. HELP! : :Cry: