I have run two lipos 2s 5200mhp 50c and 3s 5500mhp 35c and have server cogging. Many running stock gearing.
The only was to get rid of cogging in to upgrade to a sensored ESC/motor. If you have the stock ESC/motor cogging is normal at slow speeds.
Unfortunately it's almost impossible to answer objectively without knowing more about your set-up.
What motor, esc, gearing & tires do you run?
Oh and where do you run? (Grass, asphalt, snow, mud, etc?)
Seek forgiveness, not permission
Seek forgiveness, not permission...
Cogging is normally a low-speed problem with non-sensored brushless systems (trying to run a continuous low speeds as you would in crawlers). If your truck was running fine, then started to stutter, or cog badly until it got up to speed, then you have other problems, most likely brown-out caused by a servo that is going out or is overworked.
Submarine Qualified, Chief Inducted, Navy Retired