2000 rancher es 350 shifts fine in 1st and 2nd when in 3rd 4th or 5th when you get on the gas it acts like the clutch is slipping ajusted clutch but still the same

 

if the clutch fiber are too warn or steels are warped from heat it may cause this. It might not do it in 1 and 2 gear because the ratios are low and dont put as much stress on the clutch as higher ratio gears. Also check clutch springs and clutch basket face for wear.

 

try goin up a steep hill in 1 or 2 gear and see if it slips.

 

it doesnt slip in 1st or 2nd going up a hill also what are you saying the clutch basket is