1997 tacoma will not go into gear

This is a 1997 tacoma 4cyl 5 speed 2 wheel drive. Sometimes this truck will not go into gear, I changed the cup at the bottom of the shift lever and put synthetic oil in it. Take it for a ride and its fine for about 5 miles then it starts acting up again. There is no grinding like a bad synchronizer. I also noticed at times it acts like the clutch is not fully disengaging with the clutch down it has a slight load on the engine this isn't all the time though. I kind of stuck between changing the master cylinder or the slave cylinder next. Hopefully it isn't the clutch itself. What should be the next move, I guess is the question.

 

I'd change them both, cheap and easy to do.

 

What happens if you pump the clutch? If you pump the clutch a few times and it works better, suspect a hydraulic issue (master and slave). If not, look elsewhere.

 

Thanks I will change them both once I get a few other projects out of the way.