Steers to right...
I know this post is a little late, but I had a similar problem, more noticeable at slow speed than fast. It turned out that only one nozzle was steering! My mechanic found this in two seconds, as I had been having a devil of a time getting the boat on the trailer because the boat kept trying to turn right. My mechanic friend lifted the top of the steering console up to reveal the storage compartment there, then pulled the liner of the storage compartment up and out, to reveal the steering push pull rods where the steering cables attach to the steering wheel mechanism. One of the bolts had come loose, thus only one jet nozzle was articulating. All he had to do was reattach the nut, and problem solved. Hope your problem is solved as easy!