Several different things can cause and cure your flopping problem. Motor mounting height, trim angle, prop, weight distribution and hull design are the main ones. Your best bet is to have someone with experience look at it, but here are a few things to try. Put more weight forward. Lower trim angle. Try a prop with more bow lift. Do a search on how to hook a hull, but only after exhausting other options.
You did not say if you have power trim. If you don't, your best investment would be an aftermarket tilt and trim like CMC-35 or 130. It helps two ways, by adjusting trim angle and motor setback of transom. http://www.cook-mfg.com/pt35.html
As I said, a good set up guy can save a lot of trial and error, but even the best do some of it by trial.