Code P0193; engine idles rough, sometimes.

Code P0193; engine idles rough, sometimes stalls under load (D or R). Poor gas mileage, approx 25% worse, about 15 mpg.
After driving on freeway at 60 + mph for 15 - 20 minutes, then stop engine, hard start, very rough idle, engine chugs, no throttle response for 10 - 15 seconds, then able to increase rpm, but slow response. Engine misfires at idle and up through 2000 rpm. Original spark plugs, cables.
Cleaned MAF sensor, replaced air filter and egr valve. Mixture smells rich, previously detected "running rich bank 1 and 2" but does not show now.
Need help please.