There's a part inside that steering box that has an adjustment. If I recall correctly its called a reaction shaft or something like that. I believe if you take off the top block of the steering box where the hoses connect, it will expose the shaft. It has a ball on top and a flat slot in it. If anyone messed around with this it could be causing your issues.
As far as adjusting it, I cant help. Its been so long since I did one. You will have to adjust the top block when you reinstall it. The process is listed in the FSM and its very important to get it right. And do not reach through the steering wheel to start the car while adjusting this. If its out of adjustment the wheel can turn abruptly and snap your arm off.
