Gill - I have a Hensley air hitch and also a MorRyde rubber pin box.
An air hitch will not help much with chucking, which appears to be your problem. An air hitch is designed to eliminate the sharp up and down motion that can result when your truck goes over bumps or potholes and then the trailer does the same thing a second later.
The MorRyde Pin Box is specifically designed to eliminate the back and forth chucking that occurs when the truck moves away from a stop or brakes are applied, or anything else that results in a jerky back and forth motion. Take a look at their website and you'll understand. Basically, they insulated the king pin by surrounding it with a big rubber donut. And it works. The donut absorbs the forward and backward shocks.
My rig rides great. The air hitch and the rubber pinbox work well together to eliminate most of the 'jerkiness' that results from traveling down the road. In fact, it's kind of interesting to look up at my inside rear view mirror and see the pin box assembly jiggling around - Not much is transferred to me at all.
Best of luck to you.
Tim