Protobot acceleration problem , help

I have a v-5 controller w two new 393 motors that I geared for speed w 3 wire adapters, when I fully accelerate alot of the time it does this studder where it is joggy it moves and pauses ect , only when I accelerate gradually does it move smooth and not studder ? What could be the issue ?

You could be current clamping the PTC current limiters.
You can put a Digital Volt Meter (with a >=10A current mode) in series with your battery to find out for sure.
If you pick up the robot so the wheels don’t touch the ground (no load), does it still studder?
What gearing from motors to wheels are you using?
What size wheels?