Snapping sounds and shuttering when accelerating at higher rpm

Have you had fuel pressure tested, as well as exhaust for possible plugged catalytic converter?

Sounds like you need new engine mounts

ANY SERVICE LAMPS ON?

Sorry for the late reply but, no, it is not related to a loose heat shield. It is a louder rattling sound more like a loose bearing vibrating inside either the transmission or the clutch assembly. Only between 1600 and 1900 rpm. and it is not present under ou over these rpm. The rattle desappear when I lock the 4X4. Dealer is out of solution!!

if you want to reset computer disconect battery for at least 5-10 minutes and recconect if problem comes back right away and engine trouble light comes on get codes read at local garage if no light get fuel presure checked

Loss of acceleration, the backpressure noise and such are kinda tell tale signs of that converter having problems, feel the exhaust out of the tailpipe it will be warm normally have someone step on the gas and if its super hot it'd be a step in the right direction.

It should be around 2000 RPMs. Sounds like it's not going into overdrive. Probally an enternal problem.

bad fan clutch

This sounds normal to me! The engine will read that rpm when accerlerating lightly. It is the stall of the torque convertor. The oil pressure will always be higher when the rpm's are higher, or when the oil is thicker - cold.

Virbration? That is a different story. Oil won't cause that.

sounds like you have a headgasket blown, a head, or your rocker arms or lifters whatever you prefer to call them are running dry. might be time for oil change and coolant flush. If ther is no overheating or coolant smell than get your injectors checked. You might just have a broken seal that emits louder sound from the pulsating injectors. Good Luck!