"Shudder" during acceleration at highway speeds...

My '04 Santa Fe (135K miles) has been doing this for a little while.

Between 65 - 75 MPH on the highway, under acceleration, I experience what I can only describe as a "shudder".

I don't believe it's a wheel balance issue, because if I'm coasting or maintaining that speed everything is stable.

Anyone ever experienced anything similar or have any suggestions?

Anyone know of any TSB's relating to this?


Any comments would be greatly appreciated.

Thanks.

SJK