Hey, when iver I start my car it comes up the the full 13 amps. But, after about 3 mins of driving it will dip down to 8 amps. Worst part is sometimes it will die alltoghether and I cant get it started back up. But, if I fiddle with the ground it will fire up. I dont think its the altenator, because It runs for a couple weeks without doing this. Im selling my car soon, so I need help fast. Thanks guys.

 

If you want to make absolutely sure, just replace the ground cable. Make sure the ground you attach it to is paint/rust/crap free, and that should solve your problem. Cleaning the battery posts probably wont hurt either.

 

Could it be that simple? Just clean the posts and new cable? or am I looking at something more expensive?

 

Does it fire up every time you fiddle with the ground cable? If so, take care of what i listed before, and even if it doesnt solve the problem. Its one less thing that isnt the answer, but was contributing to the problem.