some think i am full of it when I say this which sounds like you are not having this problem but the battery ground on the Z goes to the tranny. I have seen an instance only once before where this bolt was loose. You might think that the car wouldn't start, but since it takes a lot of amps to start the motor, the battery to tranny ground would (temporarily) "weld" its self back upon starting and then through normal driving the vibrations would then knock it loose bc the bolt was loose. Causes very similar situations. However it sounds like you are having more of an alternator issue or other grounding issue. Just trying to help by showing every possible cause. You might want to check the fuel pump and connections as well
