i have a 93 270. Let's start with the most simple things:
1. If your boat is equipped with a Bravo out-drive and power steering, the zinc tab above the propeller should not have a fin on it.
2. Remove the center cap of your steering wheel and make sure there is no slack between the wheel and the shaft that the wheel is attached to. Re-tighten the steering wheel nut.
3. Behind the engine, coming out from the transom, there is a black steel steering rod. It is connected to the steering system by a clevis pin. Check that pin for wear and slack.
4. Make sure that you have the proper level of power steering fluid. No Fluid or low fluid will cause slack in the steering system.
Check all of these items first, and hopefully it will solve your problem. There are a lot of other things that could go wrong. Let us know how this works out.