Digital 6 Plus/ Timing ?

Everytime we drive the engine a little hard testing ' we come back and the timing is off and is running rough/sometimes will backfire a little when reving through the carb' not always..Can move the dist rest time and its back as strong as ever..We thought it was the start retard box cause it was making it run even rougher but undone it...Could this still be in the digital 6 plus' or the timing chain ? thanks

Check the dizzy. gear.

Dist was the first thing i pulled out to see if the pin was sheared..Gear still looks good as new along with pin...Msd pro billet dist...sbf

check the Dist make sure it is not moving in the block mark it to make sure....some of the dist hold downs suck and will let it slip....

I found the problem! The first msd dist i ever seen that the shaft was broke at the top beneath the rotor..The weld was still there only in a small place' but you could still twist it back and forth...This is only a month old msd dist ' but also says made in china on the box...Now it all makes since....