on the chip

Need help! I have a 02 chev 6.0 that I put the edlebrock intake for carb and the MSD controller. I have also installed a GM Hot Cam. When you try to start it, it will backfire through the carb as if you had the timing off. It will start and idle nice. After anywhere from 30 seconds to 2minutes of idleing, it will back fire again through the carb.
Here's what I have done; Checked to make sure I had 13 volts to the box when running. Checked to make sure I had a good ground. Changed cam sensor. Changed crank sensor. Unplugged MAP sensor (no change). And tried a different chip in the box. None of this made any difference.
I'm hoping someone out there has run into this and has some answers. I have called edelbrock & MSD and I'm tired of waiting on the line for ever then getting out of the book info that is no help. I'm thinking the box might be bad, but want to check every angle before I go through the hassle of sending it back and waiting for a new one. HELP!

kaboom10

I've had some experience with the developement of the Gen III truck engines. I don't think they're that different than the car version. We used to make shims up to go under sensors since the gap seemed to be touchy. What did you do to convert your fuel injection over to a carb? The experience I've had with MSD being it is a spark amplifier is it works or it don't and nothing in between. I would also check and recheck your connections and see if any wires are chaffed. are you still using a fuel injection pump for getting fuel to the carb? If you do you must run a return line from the regulator. Hope this helps.