IS200 NEWBIE

Could this be a drive shaft u joint (universal joint issue)?

Need a bit of help on this issue Owner of a 2007 IS 250 SE-L automatic, mileage is 103,000 miles (or 165,762kms) UK owner. I can’t find any information regarding the issue I am experiencing in the UK with this car but am hoping it could be an issue already experienced from you guys over in the USA and you can point me in the right direction to get it resolved? Car is in excellent condition apart from the issue described below… I have got a strange vibration that I cannot decide where it is coming from. It is only present when driving the car – in “D” or while using the paddles. The vibration is felt through the car and its driving me up the wall !!!!!. Up to 70mph when accelerating or at constant drive there is a slight vibration but this increases badly when I come off the accelerator when going down a hill for example but disappears when levelling the speed out again. It seems to be more noticeable at higher speeds and when at this higher speed it is more noticeable while keeping a constant speed or again, when taking foot off accelerator while going downhill but will decrease in vibration again when the speed levels out once again on a straight. I get the feeling its when the car is relying on the gearbox to “restrict” the speed as when going downhill with foot off accelerator, it’s the impression I get that there could be an issue with the gear box or torque convertor? Tyres are on (Avons and all good) I need to have the plugs replaced – I can’t be sure they were done at the 60k miles service interval (they may have been and should have been but I am not sure). Not sure it this can cause a vibration like this? The vibration feels “mechanical” as it sounds like driving over a rumble strip on a road but the interval of the noise is rthymic and its gradually getting worse. Can anyone help with this ?