idk if this will help or not but i had a problem similar on mine only it was with the auto trans shifter, it would not go into park or first and it only did it a really random times, finally i decided to pull off the cover to the shifter and found that there was a random bolt in there that would vibrate into a certain spot and keep the shifter from moving into park and first, really simple fix which i should have done the first time it happened but i waited til like the 3rd or 4th time and felt so stupid, take a look around something might actually be blocking it