Setting up dual joysticks

I have dual joysticks in my home cockpit which I can set up and calibrate in FSUIPC.
For reasons I don't fully understand the handling of the aircraft is not good; if I fly FSX on the desktop with one joystick it is pretty smooth. In the cockpit however it has always been twitchy. I think one of the reasons is that there is interference between the two axes. If I disconnect one stick things improve but still not good. In similar vein I find that the steering tiller inputs are dreadful unless I disconnect one wheel and even then control is not smooth.
I have tried amending slopes, I also set the minimum delta to give a null zone and I always cycle the sticks before use, I have even tried changing effectiveness in the cfg file.
The only time I got smooth control was in the dark ages using FS9 and FS Communicator, the latter will not work with P3D.
Has anybody anything to share on this topic?
Barry
www.a320sim.com