Yep, I’m with Shayne, worn or seizing UJs can give you precisely those symptoms, so check them out thoroughly, they can be deceiving.
There should be zero play in the rotation plane, but to check that you need two pry-bars or hefty screwdrivers as levers to work them in opposing directions.
I‘ve also had one seize on my 80, so of course I found no play in that. It’s best to remove the 4 flange bolts to check for seizure, it’s a bit more work, but you’ll never discover a seize with the thing bolted up.
When greasing, make sure that fresh grease comes from each of the 4 bearings on each UJ. It’s easy to see grease from one of them and stop pumping, but you end up with one bearing greased, and 3 which could be dry.
