This becomes much worse when you have the seat in the wrong position. It is very important for this boat that the seat be just right. If it's too far forward the bow will wander, too far back and the stern starts getting grabby. I have had my boat since April paddling twice a week and I just got my seat dialed in two weeks ago. I kept trying different things. For me at 6'1 190 lbs having the seat 1/2 inch behind center works perfect for me. Just try some different things.
Also try to keep in mind that a boat with this much rocker is gonna also punish any bad paddling technique. Especially if you lean back going thru rapids. Make sure you are leaning forward and using an active paddle blade.
I'm really glad I stuck with the Stomper - it really is a great boat if you want to start running some creeks and technical rivers.