need any ideas have tried almost everything....

my del sol has been acting up latley. the battery light fades in and out and the headlights and radio cut in and out when the battery light is on. i put a new battery in, that wasnt the fix, the alternator has been tested 4 times, past all four times. im now noticing an aceleration difference while the battery light is on as well any ideas on what it could be will greatly help out

it's an electrical load, no doubt. The question is whats the load? I think it might be the voltage regulator within alt as that's what causes the light to come on. I would consider an alt change even though you say it's been tested. Is your connection good at the alt? Is it good at the battery?

Check your belt tension, and not only that..if your belt is old, replace it. They slip, no matter how tight they are, and will continue to do so if they are hard and worn. I have had alternators test out beautifully, and fail to maintain 11v output when in the car...stumping me for days, until I realized that a pry bar to the tensioner would shoot the voltage right up.

Also I dont trust those auto part store testers anymore. After going through 3 days of second guessing myself with 3 different stores testing it out as "good" I took it to an alternator repair shop, and it put out less than 20A. 15 min, 20 bucks and a set of new brushes and my measly stock alternator pumped out 175A! I had always though that voltage would drop at idle in that car, and as it turns out it was a dying alternator for over a year. Long story short, take it to a real shop if you want a proper test. They can even do it in the car running if you can manage that.