I'll say it again, that engine and transmission mounts are an extremely overlooked part of proper alignment of the drivetrain in relation to the shift linkage. If they are over 10 years old, chances are they are worn out beyond usefulness. My 1982 mounts were original and sagged so badly that the transmission shift snout was nearly resting at the bottom on the bulkhead shift rod tube.
This
https://www.redlineoil.com/75w90-ns-gl-5-gear-oil oil is amazing and actually makes shifting so much better in my toyota and porsche compared to cheaper oils.