I have twin 350 MPI inboards on my 2006 320 Sundancer. I had the mechanics replace the risers and manifolds over the winter. On the Starboard engine they found issues and recommended a valve job. Sent the heads out and reinstalled them. During the sea trial for the repair, they told me the engine will not go above 3000 RPMs, and they can not figure out why. The only thing I have found for this issue is a bad neutral position sensor. Any other ideas that would cause this problem with no codes?