My 383 was acting very similar...Would be ok under low or part throttle, but as soon as I would give it a decent amount of peddle it would pop and stutter. I messed with the carb, timing, etc...couldnt figure it out.

It ended up being my coil. I went through 3 before I found one that would last more than a couple weeks. 2 parts house ones and 1 MSD blaster...all crapped out after a few weeks. I have another MSD blaster on there now that has been good for about a year and the problem has never come back.