I have a 96 f 150 5.0 wont start and sometimes starts and runs great. once you shut it off. and wait five minutes it turns over but no spark coming from coil. Tested coil its good. I replaced the brain and still same problem. Took it to shop $300. later they replaced the distributor and still have same problem. I was told to check the camshaft sensor. I could use some help here please. Tom