Well, I finally got a chance to fly Groovy again this weekend. I adjusted the CG and moved it about 2/3" forward. As soon an I did that, the high AoA tendency was gone. The plane now flies as it should and is a joy in the air. I tried different manuvers to check for proper trim & thrust angle and the thrust angle seems ok so far.

After this experience, I went home and fired up Real Flight 3.5 to evaluate the effects of CG on angle of attack. I played around with the Great Planes Yak 54's CG. Sure enough, as soon as I moved the CG to the rear on the Yak, the AoA increased. It wasn't as noticable during straight and level flight as it was on Groovy but it was very noticable during slow speeds and landings.