I have a '93 3.0. It starts fine after it's been sitting overnight, but when I try to re-start it after it's been driven for half an hour or so, the battery doesn't have enough left in in to turn it over. The battery is new, and good - in fact, it re-builds enough charge after it's been drained to start the engine again, if I let it sit for a few hours. So, it seems like when the car is running, it's maybe running off the battery. Any ideas what could be causing this??