I have a 1993 Camaro z28 5.7 liter corvet engine my problem is some times the motor cranks over hard then some times it doest what ive replaced on the engine is water pump opti thermostat ignition module coil and I took off the harmonic balancer to change the opti I don't think I have it on right is there a certen way its suppose to go on. help please

 

hmm. Seems some mechanical problem. Have tried taking it to the dealer??