arhg! Very complicated electrical prob...?

I’ll give the short version, or try
After getting my system & half the engine comp. ripped off, I replaced the stolen intake w/a civic APC job from pepe boys until I could get the right one. It didn’t really fit in the space, & two weeks later, basicallt cut through the power (battery) cable…the ground terminal melted & both battery wires were shot. I replaced the battery & wires. Now…
The cars electrical power keeps cutting on & off. The ABS light will cut on, the radio cuts off, as well as the headlights if I’m driving. It will happen @ every two minutes or so. Sometimes, after a while…the check engine light will come on and the s3 light on the transmission indicator lamp will flash regularly for the duration of the trip. The car does not stall. It seems to want to do this more when I am stopped.
The mechanic first said he tightened down a ground on the transmission, which seemed to fix it for like a week. Now he wants nothing to do with it (he says it won’t replicate for him).
Any suggs? I’m a shi**y mechanic, and this has me totally baffled. I thought I’d ask some of you all before I get reamed at a mechanic I don’t know.
TIA

Ah ha!

Well, for anyone who’s curious…
I went over all the connections I could think of and found the culprit. The ground wirefrom the valve cover to the chassis was shot. It was not apparent at first glance. What had happened was the wire itself, I think @ 10 gauge, was frayed pretty badly within the crimp ring connector, which itself was kind of a weird design; it had two crimps with a 1/2" space between them. the exposed wire between these was pretty crappy. I bought some wire and ring connectors, and replaced this setup as well as the other which goes between two nuts on the valve cover. All in all, a silly story, but it was a good lesson for me to really check things closely and NEVER ASSUME.