LS170 Hydro question

[skeeballhead]

I bought a 2005 NH LS170, has 550 hours; super nice shape. My question is in regards to the hydros'. What would cause them to be so jerky. At times, it feels like it wants to buck me out of my seat, especially at full throttle. My friend's L180 is crystal smooth. Does this in forward and reverse, turning, etc. The controls seem fine for bucket and so forth. I realize it is a longer wheelbase machine and has the 12X16.5 tires, but I would really think my LS170 should be a smoother operating machine. Any ideas of what to look for, besides just taking it to the dealer and saying "here, fix it"? Thanks.