Problems will not go away....

This all started two and half years ago when the three speed went out, and I had to collect the parts to convert it to a four speed.

Did you collect all of the "correct parts"? Was the trans gone thru before installation? How bout the pilot bearing? What type did you use? Was the crank drilled to accept it, depth-wise as well? Just asking some questions that may have been over-looked.

How can it be stuck in 2 gears at the same time?