Most of the research I did indicated this was a 1st gen Tacoma problem, but I'm sure it must carry over to other models and years because the parts in question are used in many other models.
Vehicle is a 2004 Tacoma Xtracab 2wd w/5 speed manual transmission. Approx 60K miles. Normal maintenance including synthetics throughout (engine, trans, diff) and new tires, everything else original.
I started experiencing shifting problems last winter (2016-2017) like the trans wasn't going in gear all the way. Then 2 weeks ago trans started popping out of 3rd and 4th gear occasionally. I knew it wasn't a clutch problem so I was thinking maybe a linkage problem. Anyway I discovered a quick and cheap fix.
Toyota Part No.: 33505-35020
SEAT SUB-ASSY, SHIFT LEVER
Toyota Part No.: 33548-31010
BUSH, SHIFT LEVER
Genuine Toyota parts are about $20. There are aftermarket kits but there are some fitment questions, so I went OEM.
The Shift Lever seat assy deteriorates over times and the shifter will not travel all the way to make complete shifts. Mine was so far gone I had to vacuum the pieces out of the shift housing. If you search "tacoma popping out of gear" or something similar, you can find tutorials and pictures of how to do the repairs. I was thrilled to do this fix because I was starting to think it might be a more serious problem.