1996 Mazda 626 5th gear pops out

You're not alone, mine started doing this last week.

I have a 97 626 and it started just popping out of fifth when I took my foot off the gas. Now it won't go into fifth at all, it feels like it engages, but when I release the clutch all I get is grinding like the gears never quite got together.

Have you found the problem yet?

From what I can find out, most likely, it's either the shifter linkage bushing, or worn/broken engine mounts. I just parked mine and have been driving my other car until I get the chance to get under it and take a look.

Your problem is worn gear/syncro if no noises and reverse works and you don't want to spend a lot of money. Get a bungie cord attach it to seat ,console what ever then when you go into 5th hook it around shifter.
Old School

Even with the shifter pushed all the way up into fifth, it's still not engaging into gear. It kinda feels like the shifter needs to move forward another half inch or so. All the other gears including reverse work perfectly.