Hey man, FWIW, if you are setting the timing at 8 all the way up to 16 with the bypass unplugged, your computer will pull all sorts of timing out in the mid to full pedal. Your truck should idle max at 16 with the bypass connected. I set mine at 0, even 2 degrees I had some knock on the scanner...
My number one would be to fix the gas leak. Number 2- Make sure all the ground wires are in good order. Block to frame, cab and the ones on the front of the motor. Replace any that are gummed up. From the sounds of it, they are probably not and that could cause any or all of the above other than...