I have an 88 daytona 2.2 turbo. It isn't charging very strong actually kinda weird. When I run my wipers the gauge jumps around, headlights go dim and bright at an idle. The car starts missing when the charge gets really low. The battery has never failed to start the car. Every now and then the belt wil squeal and it's almost guitar string tight. The alternator has tested good using the autozone tester. Any Idea whats causing this?