A friend of mine had a similar issue once with a ground adjustable prop; lower than desired rpm for climbout, but yet would very easily redline in straight and level flight.

We flew together half way across the country trying to figure out why his plane performed so poorly compared to an identical one just like it with the same prop and engine. What we ultimately discovered was that one blade was adjusted with more pitch than the other (that specific prop had a very sensitive and difficult to adjust hub). After setting both the same, his airplane performed just like the other one we were comparing it against. It made a huge differnce.

So I would make absolute certain that all prop blades are adjusted EXAXCTLY the same. We used at that time an electronic level to insure the most accurate measurement. Then we played around until we learned the best technique for tightening the hub bolts. Most importantly is checking the prop not only for proper tracking, but to assure both blades are pitched exactly the same.

Might sound trivial, but I would say having one blade off more than the other(s) would be the equivalent of having one wing on your airplane having a different angle of incidence than the other. Imagine how poorly that would work? Well, a prop is in effect just a wing...

Paul S