M42 won't hold idle UPDATE: New problem. Need help

[uturn]

The last time I had a car act like this was because it had a cracked cylinder head.

[shameson]

I think the issue was found. Had a spark from near the alternator when it was revving. After pulling the alternator we found a spot where it looks like the ground was arcing causing a mark on surface of alternator.

Had the alternator tested and it was at 14.2. The alternator ground strap probably is the issue. Strap is poor shape with multiple tears in the insulation. Used a volt meter on the battery and was only at 11.75, so there's certainly an issue with alternator charging.

Going to test the alternator with a new ground strap and see what happens. The throttle cable is also in poor shape and will be replace as well