My 1993 GMC Sierra, V8 just quit running while I was driving. What would be the problem?

Are the fuel injectors spraying fuel. If they are not try the pick-up coil. It is in the distributor plugged into the ICM. You will have to pull the dist to repair ensure you mark the position of the dist/rotor ad start at a known point like TDC on compression incase the motor rotates. (The pick-up coil is referenced by the ECM via the ICM for engine RPM and will not inject fuel until you pass ~ 400 rpm of fuel). If the injectors are working and you have good spark at the plugs check the timing and or the fuel pressure. Could have a plugged fuel filter, fuel regulator issues or the timing may have jumped. I've got a '92 the ICM has went 4 times the pick-up once and the regulator in the TB has plugged once. Original fuel pump knock on wood.