I just did this, and now I'm having problems. I replaced my factory battery ground cable to the starter, and to the chassis. I also replaced all of my vaccum lines.
I did all of this in the parts store parking lot, and drove home. It ran better at first, but then then engine would quickly stumble under higher load. If the cables good, the only thing that I can think of that might help is putting in a new plastic cover inside the distributor. Half of mine broke off, and now my coil isn't shielded from the cap and rotor.

Could running the bigger cable do anything bad to my distributor internals?

 

That shouldn't affect it, I run 4g, did you recheck all the connections for corrosion and whatnot before you connected the wires??

 

I still haven't looked at it yet. I'll have to take it back apart and go over everything again. The surfaces could be cleaned up a little better. I'm 99% sure nothing's loose at all, though.

Hmm, after checking out this site, I think I have a vacuum leak instead of an electrical problem.

http://www.aa1car.com/library/vacleak.htm

I forgot to mention that my idle speed was high after doing this. I forgot that I had adjusted it down in a parking lot. Hmm, come to think of it, that's when my problems got worse.

I'm pretty sure I've got a vacuum leak now.

 

Your idle will be high if you have a vacuum leak. You can even test this if you unplug a vacuum hose you can see the change in idle. I'd look them over first for leaks or clogs although they shouldn't be clogged since you just replaced them.

 

Vacuum leak!!

 

I replaced all but one of the vacuum hoses with smaller size tubing that seemed to be less prone to leaks, along with installing a new inner distributor cover. It runs a LOT better now! I still want to fix my exhaust leaks near the cat converter, replace two injector seals that I know are bad, and install a new fuel pressure regulator.

 

awesome, it's always relieving when your car runs better again