[THEFERMANATOR]

Take the shift cable loose from the engine, and try and move it by hand and see if there is any binding in the linkage at the engine. It is pretty common for the shift linkage to get tight where it atatches to the block. Theres a grease zerk for it that most people don't know is there, so it tends to not get greased, and this in turn over time allows the grease to harden and makes the linkage sticky. If not that then your shift cable is probably getting worn internally.