My '89 7.3 did that dying thing for a while, then I turned up the pump and it has not done it since. Maybe mine was running kind of lean, I could not make it smoke one little bit, but now it smokes like a train!!!!! The power is good now, huge improvement! The idle sticking up high sounds kind of like it may have something to do with the linkage to the pump, check the spring on the throttle arm on the injector pump maybe spray some wd-40 on the linkage. I don't know, those are some places I might start, there are a lot better mechanics on this site than me. I am almost positive there is no cam shaft sensor on these engines, I have had them go bad on powerstrokes and they can do some crazy stuff! Good luck, maybe somebody else will have a better answer for you.