Why is my 95/96 Toyota Tercel 4 speed manual popping out of gear?

What is your question?

Everything is fine in first and second but it occasionally pops out of 3rd and won't hardly stay in 4th gear at all even if you hold it there, it pops out and then grinds and the shift knob jumps until you put it into neutral or into a different gear could this still be the shift linkage bushings or is this something from the synchronizer in the transmission? (Just got the car and haven't been over 60 mph... Plz help)