V70 judder

[Bigblue74]

Hi folks
Wondering if anyone can give me any pointers, while driving to work this morning my car developed a nasty vibration, the only way I could describe it is it felt like the car was chugging, as if spluttering to a halt, however dipping the clutch made no difference at all and the engine revved fine and performed perfectly, so even freewheeling the car felt bad, I pulled over to check the tyres etc and all seemed fine, when I pulled away again it all seemed okay until I hit 60mph (ish).
It didn’t feel like the usual wheel balance problem, it actually felt like the entire car
I dropped it off at a garage next to where I work and they got it up on the ramps, nothing obvious showing at all, they also test drove it and it was fine, I’ve tried it since and it’s fine again, very confused over it.
The only thing I can’t relate it to was when I had a cv joint fail a few years ago on an Audi but that did the clicking when turning, my Volvo has none of that.
Is there anything anyone else has come across that’s anything like this ??
Thanks in Advance…..Gary v70 2.4d manual 2010