6.2 diesel help

[big_bad_jeep]

i have a suburban with a 6.2 it run great it has 36inch hummer tires but my biggest problem is its gutless, when u hit the mud it goes a lil and its like a brick wall and the engine cant spin the tires its like it just stops due to no power is there anything i can do to help cause i wanna go on the trail ride saturday?? i heard turning up the injector pump but i dont want to mess it up.