hi all i am new member and i have big problems i need help

I have a 2000 Xlt , electrical switch 4X4 that has been having some engagement/disengagement issues .
It always shifts into 4x4 hi or lo just fine, sometimes its disengage win i want to claim a hill and hit the accelerate to the max .
after i riles the accelerate it will engage .
help me plies.

 

is it in 4 lo when u hittin her hard? its not made to go that fast in 4 low. and welcome to the sight! im new 2

 

Either the front axle lock up collar is slipping out of engagement or the transfer case is slipping out of engagement.

 

also could have a hole in the vacuum line going to accuator piston on the front diff or diaphram leaking as well

 

thank you all i will cheek and com back