sounds like it. its flywheels responsible for judder, but usually at low revs and on 1st gear...
Did you check the flywheel for up and down play ? there is up and down play, and side to side play. these will have different effects i would think. maybe up and down play while driving in general and side to side only when low rev torqued. In any case sounds like you need another flywheel. you can get them on ebay checked for play with 7 day money back if not happy for about 50 quid now.