Problem Defined!
As suggested, I found an AUTOZONE parts retailer where they ran diagnostics tests on my FORD E350. Upon my request, using their "FIX FINDER" to list trouble codes, they were able to determine the Throttle / Pedal Position Sensor was the culprit causing the Idiot Light to illuminate.
The Technician at the counter was kind enough to explain. Simply put, the connection between the accelerator pedal and fuel flow is electrical. Not mechanical linkage. Switch A and Switch B share an acceptable range of voltage.
As he pointed out, the error also causes Cruise Control to disengage. A very knowledgeable individual, with a lengthening line of customers building, I refrained from asking additional questions. One being: what prompted the Idiot Light to disengage? About a half dozen engine off/on cycles??
Generally speaking, a Throttle Position Sensor (TPS) is fast and affordable to get replaced. It is located on the throttle body, an easy project, even for a shade tree mechanic.
I would get it replaced ASAP. Today it's a light on the dash board. Tomorrow you might have strange drivability and/or lower gas mileage.