My car wouldnt start at the gas station!!!!!! I almost died!!!!!!!

[vetteeatr]

K guys heres the deal. I bought this 88 mustang Gt with a 5.0. The car was used for drag racing and simply hauls. Anyway performance crap out the *** and so forth. But my probelm is if i let my car sit for a little bit it wont start. I dontg get it and its kinda pisisng me off. Also it was getting the battery drained whiel i drive it at night with the lights on and so forth just slightly. I have no idea why and its getting aggravating. THis jsut started happenign about a day after i bought it naturally. Anway i talked ot some peole and they said the alternator voltage regulator can stay on after the car is turned off and drain the car really quickly. But still why woudl it be drainign at night then when its running? All suggestions are helpful. We couldnt find any massive power drainers whe the car was runnign when i took it to Autozone so im clueless. Thanks