1990 Cadillac Fleetwood

Engine problem
1990 Cadillac Fleetwood V8 Front Wheel Drive Automatic 200000 miles

I recently replaced the alternator on my 1990 cadillac fleetwood and now my engine idles extremely rough. I dont have the money to take it to a shop and I dont know any cadillac mechanics. I dont have very much knowledge myself. When I put it in gear it rides fine until I come to a complete stop, and I'm starting to notice my brakes slipping as I'm slowing down. Could any of this have to do with the security light that pops on and off again, the same with my check engine light. Im pretty confused and I need the car for work. Please help!
February 15, 2008.

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