Going back to the basics- here is why:

Syleng1 said
So the 66’ progressively is getting worse when I step on the gas. Breaking up and hesitating and just running like dog snot.
Checked timing, thru in new plugs (old ones looked great.) Ohmed out the wires, checked the cap, and nothing to write home about. Then, at 4am this morning I thought about the ignition module. GM 4 pin hei.
Sure enough- pulled it this morning and found a crack. Changed it out with a new Napa and runs good again.
Allways check your basics. View attachment 1716242372

Yep. Had a instructor in tech school preach that. Oh, and "never overlook the obvious". SOmetimes the simple things will bite you in the butt if you don't pay close enough attention. The GM HEI would be my first choice if I was to go electronic. I have the original dual point in my 66 and it works perfect. Pertronix in my 70 which works well. Instead of Mopar's electronic, the HEI would be my choice. 12 volt, no ballast, and no junk ECU's.