overheating 1994 SeaRay 230 Sundancer

In the last year or so, I had some engine work done on my 1994 SeaRay 230 Sundancer and ever since, it overheats when you go WOT or over approx 3200 rpm. A new impeller unit was installed as well as a new bellows unit. It runs fine below 3200 rpm's. Has anyone else had this problem before and if so how did you fix it? Any advise would be greatly appreciated!

Todd