really embarrassing...sometimes right when I let off the clutch and go to get on the throttle it will not be in gear, causing a loud rev. also, sometimes when it does go into gear, it will just pop out.

 

Worn synchromesh baulk ring,or defective gear interlocking device,or seized clutch release bearing.

 

My 99 civic did the same when I put a b16 in it. I took apart my tranny and found that magnet broke off and that was cause my 5th to jump out of gear. Rebuild tranny just make sure every part goes back exsactly where it goes.