1996 Ford F350 EGR valve @ idle air control valve

7.3L diesel engines are not fitted with EGR or IAC valves they are fitted with :-

Idle Validation Switch (7.3L DI Turbo Diesel)Near accelerator pedal

Idle Validation Switch (IVS)
PCM uses IVS signal to verify when accelerator pedal and shaft is in the idle position. Any detected malfunction of IVS will illuminate Malfunction Indicator Light (MIL) and engine will operate at low idle only.

Exhaust Pressure Regulator (EPR) (7.3L DI Turbo Diesel)...On top center of engine.

Exhaust Backpressure Regulator (EPR)
EPR is a variable position valve that controls exhaust backpressure during cold ambient temperatures to decrease amount of time required to warm engine up. PCM uses measured exhaust backpressure, ambient air temperature and engine oil temperature to determine desired exhaust backpressure.