I have a 91 Caravan with a 3.3 motor. after not starting I got a code 11 which I replaced the cam and cranch sensors. also replaced coil and compter. after this still won't start. it fires on 2 cylinders and checking coil other 4 cylinders not firing. I bump the engine enough I will get a spark from 2 other cylinders as I let of the starter but will only happen once in a while. any ideals what is going on