I have a 1998 Range Rover 4.6hse and when I step on the gas the I hear this thump-thump-thump under neath the truck and I lose power, it used to be when I stepped on the gas hard but now it has gotten so bad that I have to let the truck coast to about 10 miles per hour and then gradually ease on the gas and when I get going im fine but other than that on guy told me it might be the viscous coupling or the transfer case chain. If somebody knows something please let me know thank you.
I have not even had the truck for a year yet and it has 90,000 miles on it and it is already given me problems this sucks

 

wow could be a differential,or maybe the t-box.my advice is take it to the dealer.just to let you know if it is a vicous coupler in the t-box your lookin at a 1400 part and alot of labor since range rover t-boxes are not available