My 99 with a 5.4 and automatic transmittion
during take off from a dead stop there is a thunk about 2 to 10 miles per hour cant tell for sure but it seems like the transmittion
fakes a shift, anybody else had this problem

 

check midshaft bearing in drive line

 

Lube the splines (center and where it goes into the trans) in the driveshft too