I just had my EVO9 clutch changed at 26k mile a month ago. I felt the clutch was pretty new right after they changed it. I have been driving it for a week or so with no problem. but today, I have an issue that fifth gear drop back to natural right after I shifted it. it happen 1 out of 5 times when i shift, even on highway. what may possibly causing it ? I am not sure does it has anything to do with the new clutch ? any advise would be appreciated.

 

More than likely it's a synchro issue.