i have a 05 5.4 manual 4x4 on floor when its in 4high it sounds like a vacuum leak when in 2wd it like there Is a trailer on the back pulling the truck down. tuned up about 5000 miles ago dropping tranny pan this weekend for filter change 95000 miles on truck

 

Try changing your diff fluid. I just had my tranny and diff fluid changed and I noticed it ran smoother off the line and at idle.

 

ok just change fluid in transfer case its smother but i noticed that when i spin the front wheels the axle goin to transfer case spins to is that normal or should they spin free kinda lost my other trucks have had manual locking hubs. thanks for the help