Geo with shifting problems

My 1990 Geo Prizm has been having problems shifting into fourth gear. When my wife or or try to shift into fourth gear, it just doesn?t seem to catch without several tries. As far as we can tell, the problem is only fourth gear. We rarely use fifth gear, but did a short test run and didn’t have any problems. In what might be a related, but as yet unreplicated, problem: the other day my wife had problems making the car go smoothly in first gear. She said it felt like the car was lurching and shaking, like when your about to kill the engine getting the gas and clutch balance wrong.

Perhaps the shift linkage is worn, damaged, or needs to be adjusted.

Does the transmission slip out of gear, or is it just difficult to get into gear? If it stays in gear once it’s in, it’s probably the linkage.

It stays in once we get it into gear. We get the shifter in position, take our hands off and it pops right out.