I've recently Installed an MSD in-cap coil, wires, cap and rotor, bought a module but was not the correct one. Installed everything but the module and now it drives smooth for about 5 minutes until there is erratic rpm fluctuations. It is drivable but I don't want it to continue struggling all the time. I was thinking possible reasons are fuel or the ignition module should be replaced as well. The Coil is brand new and I don't believe it could be the problem.

If anyone can help I'd appreciate it. I've read a bunch of problems that sound like mine but I've narrowed it down to what does it.