Did you install the drop bracket on the tunnel shift bracket? If so, sometimes the shifter can get hung up on the bolt heads. On one, I had to counter sink the holes and use flathead machine screws....
Or it could be that your shift linkage needs to be adjusted...
Or it could be that you didn't install the drop bracket and the torque rod is out of alignment....
Or if you don't want to deal with any of these, follow the great suggestions above and get a Novak or Savvy cable shifter....

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