87 gt charges intermittantly

so far i went through 2 batteries and 3 alternators, i checked all the fuses, it only charges intermittanly, it will die while im driving, it will hold a charge when not started but once its started sometimes it will go for a few miles, but others it will die once it gets down the block, any suggestions?

sounds like you have a bad charging system relay or bad ignition relay

replace plu to the alternator!