My firing order was off (3 & 7) were mixed up, so I fixed them and replaced those plugs, it was running beutiful, but now it runs like it's missing a cylinder sometimes, but then at times it will run perfect, anyone have any ideas on what could be the problem

 

Sounds simple but did you check all the wires and make sure one didnt come off the plug a little? If so you may check the plugs cause it sounds like you have a fouled plug imo