Its an old Plane and probably is a bit of a dog but dont forget the "getting it on the step" dodge.
ie. Level out at your cruising altitude but leave full power set for a few seconds so you accelerate to slightly faster than your normal cruise speed. Then reduce power to Cruise RPM (2300?) and re-trim for level flight.
You should find the 150 is flying level, rather than staggering around the sky in a slightly nose up attitude. It should "feel" a lot better.
Rgds