I've never believed that Darth Vader's Force abilities were hampered(other than Force Lightning, which you need flesh and blood hands for) by his cybernetics, but his physical abilities absolutely were. I imagine it would be much more of a challenge to run, jump and flip like they do in the final battle of Revenge of the Sith while wearing a big suit of armor and having your oxygen regulated because you can't breathe for yourself. You could say he could use to Force to augment his physical abilities, but then obviously he can't be doing everything at once, so that would disrupt his focus on any other things he might be trying to do with the Force. So while his Force connection remains, as is evidenced by his total raping of Luke with floating objects in Empire Strikes Back, he's in no condition to take on his former self.
"Everything I tell you is a lie. Every question I ask you is a trick. You will find no truth in me."
―Vergere to Jacen Solo