Was not totally EGR Valve
I Replaced the EGR Valve and Valve Position Sensor, then cleared the codes and test drove it. Still running rough and getting check engine light when truck warms up to operating temp. Checked codes again and EGR codes are now gone but still getting 173 (HEGO sensor voltage signal indicates "rich" bank 1). Sensor voltages metered OK and sensor looks in good shape. Could old plugs cause this. I pulled one out and it looks pretty bad, going to replace them. Thanks to everyone for the advice so far, could use some more. One more dumb question...which side is bank 1?