Took the car to a local show today, went to hope on interstate to leave and I romped it, got to about 4K and it fell on its face and started popping/backfire out of exhaust. Lifted and was fine, roll back into it and same once again at about 4K. At this moment I think electrical, I have a new msd 6al box, and new msd pro billet dist with mechanical advance. I removed the ballast resister with the new msd stuff. For a coil it’s an Accel super coil 140001, it’s about about 7 years old and use to run it with old stock ignition stuff. At the moment I’m thinking coil? This is a new issue, had the car at the track last month at the nats and was running great up 5,500 rpms. Any advice?