2001 neon runs rough at idle runs fine at any speed Changed plugs and added fuel system cleaner Any suggestions?

I would suggest you remove the air cleaner element and with a tooth brush and Carb cleaner clean the throttle body hold the flap open with a screw driver or something.

the upper part is likely the most important.

If That dose not work to your satisfaction you might try and remove carefully without damaging the gasket the idle speed motor mounted on the top of the throttle body & clean it with carb cleaner and a tooth brush as well.