This is my 87 GT........
When my A/C is turned on my batt volt meter drops low. I think the alternator is the prob. I searted the car, removed the positive post and the car still runs, however when i switch the A/C or headlights on it stalls. What do you think is the prob?

I had my old Alternator and Battery tested and they both passed. I still purchased a new Alternator the problem is still there...Any ideas whats wrong?

 

I'm going with a poor ground connection. Check the neg lead from the battery and the misc stainless straps from the block to the sub frame.

Does it do it with just AC or just headlights or does it have to be both?

 

Check all the grounds and sand where it bolt to for a clean/good ground.

 

the 5.0 alternator sucks... its not even really enough for the car. do a 3g swap and get it over with

 

true dat, especially if you throw on an underdrive pulley