Hi Bobb, welcome to the Forum.
I've got a 34, admittedly 2001, with the original MD2030 engine/prop combination and I have never had any swerving at any engine speed to +3200rpm. It will also hold any turn to port or stbd under power without deviating. Have you had the boat out of the water yet and if so, was there any play in the rudder bearings? Is it possible the rudder has been reversed into something, bending the stock forwards at the bottom? Those are the only things I can think of that might cause the problem. Some of the more experienced people on here may be able to throw further light on this, e.g. unbalanced prop, etc.
Cheers