Help - Car pops out of gear Options

[Stu37363]

I have a very limited knowledge of transmissions and was hoping someone here might be able to diagnose my problem or tell me what to check.

Lately when accelerating in 4th gear, the shifter will pop into neutral.
3rd gear has always pushed itself towards neutral while accelerating, but never actually went into neutral.

In 3rd or 4th gear i can hold pressure on the shift knob and feel it pull towards neutral when accelerating, then if i release the throttle, it goes back fully into gear.

Recent car changes:
Teaching daughter to drive a manual. there have been some rough clutch engagements lately.
I recently bottomed out on a speed hump
my front motor mount insert has deteriorated (haven't checked the rear mount, i had installed kirkasaurus mounts years ago)

Im hoping maybe i just need to adjust the slack on a cable somewhere.

Any thoughts?

This post has been edited by Stu37363: May 23, 2016 - 6:49 AM

[Stu37363]

No grinding at all when shifting. i was just under the car a minute ago, and the rear mount insert is gone completely. the rubber looks like it may have a crack in it, but its hard to tell until i can pull it. I went ahead and ordered another set of poly inserts, and i may pick up another rear mount. Supposedly the inserts can be used regardless of the rubber condition, but im not sure i like that idea.

I am crossing my fingers that all the items i listed as possible issues worked together to destroy that rear mount, and thats all i need to fix. I will try to follow up this weekend when i have time to work on it. hopefully i get my inserts by then. Until then i will keep checking here for other responses, and just avoid using 4th gear for now.