a slight bump on highway

HI,
I would appreciate everyones input on this issue that i have noticed when driving Diana.

After accelerating and let off the gas i feel a slight bump. This is the only time i have ever experienced this... I never did on my previous 2 other supras. Only on Diana right after i let off the gas when driving on the highway past 65-70mph.:3d_frown: I dont like it, cuz i dont feel safe once i have felt this slight bump.

What is it and how can i have it fixed if at all possible.:1zhelp: