Why is it that T-tails want to climb like on a PA-44? It seems like it always wants to climb
Because of the location of the horizontal stabilizer, it isn't as affected by the power setting. Thus, it's likely that you are trimming to compensate for power reductions when you don't need to. I would make sure you trim well, and ensure you are trimming based on what the airplane needs rather than what you would put in on a Cessna.