Stumble at initial full throttle

Pulled the carb, it was fine. Replaced the orange ignition box with the blue one. Engine idles rough and will not idle below 1000 rpm. Timing is set at 12 degree initial. Above 1500 rpm the car pulls hard in all 4 gears. when I shut the engine off, it will diesel. When the car dies at idle, it will also diesel. I am at a loss.

Thanks

Pa karp