Mechanic Said I Have Bad Wiring Harness On Engine?

I didn't even know than an engine balancer was a thing. How would I check it? My alternator should be here soon! I'm pumped. Other than that, I'm 80% sure they were done when my coils were done a few years ago.

Ok, Update! So I installed my new alternator + extra wire, and turns out that it actually runs AND the weird vibrations at idle are no longer there. However, it's been replaced with a new problems (woo money pit!) namely the fact that it'll idle just weird. Almost too slow? Or too low, I'm not sure how to describe it. The engine almost Lopes..like I've got some cams. Boy do I wish. Any one have an idea what I can do before I take it into a shop?

I have put some miles on it, idle hasn't cleared up, so I'll disconnect the battery to let the car relearn how to idle. Next up is it feels like the car is losing power for a split second (and I'll have this feeling several times throughout the entire range of RPM, in all gears, at all speeds) when I punch it. The best thing that I have to compare it to is a few years ago, when I first got the car, a couple coils went bad and weren't firing reliably. At the rate I'm going, I'll say screw the mechanic, because its already been into the shop twice for issues with Something electrical on top of the engine.

Long story short, the car runs, my battery is no longer getting drained. I won't worry too much about the idle until I run it with the battery disconnected. Now I have what feels like power loss or a hesitation. Is that also something that could be caused by the cars computer not being familiar/me not having done the proper procedures..or is there something else I should be worried about besides doing spark plugs next week.