Swapped my 6 al to a digital 6 and now the car breaks up around 3500rpm popping thru the carb and exhaust

I check the timing after the box swap and was advanced to 45 so I brought it back down to the 34 I normally run.

only thing I did was swap boxes

everything was fine with the 6 al

it is powered and grounded at the battery

The pick up wires for the distributor is in the same spot with nothing around it

I had the same problem with 8975 retard with the 6 al removed that and put a dial style retard in and problem went away

I Wire remote starts and stereos for a living so it's not my 1st time around wiring

Any Ideas?

Thanks

Phil