Today while driving home from work my 2007 jku 3.8 start to shake really back and had little to no power at lower RPMs. It vibrated pretty good while during home. No smoke no leaks as a could see. I took out my superchips flashpaq and got this error code P0302. no sure what to do? It could be a simply spark plug or it could be a spun bearing which mean engine is toast. Please help with comments on what to do.