FD 1/8 Buggy Stutters

Hey guys. I picked up a used FD 1/8 Scale buggy. Torn it down and rebuilt it so I know all inerts of the buggy are ok.
Got it all hooked up programmed the 9920 and disabled the BEC, Running a 5 hump 1400mah and a JR AM radio.
Here is the issue: I can ease into the throttle and it goes ok - sometimes even at 1/8th throttle it will stutter (like the motor turns off and then back on). When I attempt full throttle it hesitates like crazy trying to find its self then it will grab but will soon release (stutter or shut off/on the motor) I almost makes a barking sound.
Any ideas?

Thanks