I have a 2003 SSEI and am experiencing a new issue with the car. When I got the new engine in the car I put a battery from one of my Grand Nationals in it. Everything was fine for over 2000 miles. My fiance left her door open and the car went dead overnite.. I jumped it the next day and all seemed just fine. It went back up to 14+ volts. The following day it dropped to 11.9... I said screw it and ordered a brand new alt and went and bought a brand new Battery. I put the battery in ....same....today the alt came in and I installed it....same! Any ideas? This is driving me nuts!

Have you checked the wire that goes from the battery to the alternator?

I have not had a chance to check the wires. I will do so early tomorrow. I just want to get as many ideas as I can

Well, you changed the alternator and the battery, and still having problems. That kind of only leaves the wire.

Dont forget to check for drains on the battery, things like the trunk light or dome light.
I put a new battery on my girlfriends car last summer and it was defective, car would start fine for a while then fail to work. I was rearing my hair out 'til I figured it out.