I have a 1990 Nissan Pathfinder. When driving the 3rd and 4th gear grinds between shifts. Also whenever the accelerator is released it will pop out of 1st 2nd 3rd and 4th. Anyone has any idea why this is happening or what is the best solution to the problem. I also see that the gear sticks jerks forward and back between acceleration and release.

Check your engine and trans mounts are they soft or worn out?