I have a 91 w150 with the 318 engine. About a month ago I was driving to work and I let off the accelerator and the engine died. I figured it was time for plugs and wires and cap and rotor. I replaced those and I still have the problem. However the engine doesn’t die all the time. The engine idles really low and the power steering doesn’t work. Any thoughts before I start replacing parts?

 

It's most likely your idle motor(ISC), It sits on the drivers side of the throttle body.