I have a 95' Chevy 6.5 TD. Its kind of hard to start, I have to put my foot on the pedal a little and try and start it. I have to feather it till it will stay running and then its fine, but it has a miss. It smokes a lot when it is first started and until you drive it a ways then it will stop. It drives fine for a little then it will start missing. If you try to get on it a little when you pull out of while you're driving. It hesitates/breaks up and carries on. I'm thinking it might be the optical sensor or PCM that is throwing the timing off etc. Can anyone help me?