So I figured out the issue, it was a combination of old plug wires and Rotor phasing issue. I bought a new coil, a crane cams ps92, installed it, and the issue was still there at 2500 rpm. After that I installed the new spark plug wires that I bought, and tried it and the problem was a lot better. Then I decided to try un-plugging the vacuum advance and it's gone compeltely. So now I know this is a rotor phasing issue on my brand new firecore 50 distributor. Not exactly sure how to correct this problem. I hooked my mitt vac pump up to the vacuum advance, and applied vacuum untill the arm was fully pulled back, and I checked the gap at the reluctor teeth and the pick up coil post and all 8 of the teeth were exactly .008. So Im 90 percent sure this is a rotor phasing issue when the vaccum advance is applied.
