I do agree it sounds like it could be the throttle body but I'm not fully understanding what it's doing. I thought it wasn't drivable at all. like put in gear, hit the gas rpms go up truck doesn't go anything.
can you take a pic of what you're using to read codes? I only ask cause I've even see a code like that in my life from any scanner. got me curious.
so the truck drives some times but then dash lights come on, says reduced power. you hit the gas but nothing happens? it doesn't rev up the engine or anything, just like the throttle pedal is dead? that sounds throttle body to me. but total shot in the dark without some fault codes that show something we can look up. like said about the codes usually start with a P like P0300 is misfire code. things like that. I don't know the throttle body code off hand, but I'm sure there's one for it.