02 7.3l check engine light

i have a 2002 f250 with a 7.3l that has a 186000 miles on it.
my problem that i cannot figure out is my check engine light comes on and when i hook up a code reader it dont give any codes. when the light is on the truck runs fine its maybe a little rough but it runs and idles with no problems. once i get in it and drive for a bit the light goes away. some times when the light goes out it will sort of kick i guess would be a good way to describe it. and then it runs real smooth. and then other times ive had it to where when the light goes out it gets a really big boost of power and the pedal becomes really touchy. and then some times it will go out and it will build 6-8 psi of boost between 1500 and 2000 rpms and it will black smoke. also some times if im going from 55-60 mph and slow up to turn into a driveway the truck will stall mid turn. im not real sure what the problem is. so far i have changed my fuel filter and changed my wiring harness on both sides. i changed the wiring harness because the truck would miss. also i have changed my timing sensor and this made no diffrence.