I have a 94 z28 camaro that has no spark at coil and has no ground at injectors. during a burn out the car just shut down. before that it had small amount of smoke and had hesitation at high speeds. I have ground and power and 4.7 volt between pcm and opti. I replaced coil to stock. I used a snap on scanner but it did not show a code. it is ob 1. also before failure it had would take alot of ignition cranking to start[:@]. is there anything I can test before just replacing the opti. I am not a mechanic by trade and need some good advise. The only thing I have upgraded on the car is the air intake.