Find a good mechanic....and save yourself a bunch of guessing and buying and replacing parts that don't need it...all the things listed could be the cause of the problem..I have a 93 with 5.7 and a 99 with 7.4 both have done similar with a different thing that were wrong...
The 160k mileage range I had to replace the whole distributer one time and fuel injectors and a fuel pump...all acted similar..
If it ain't broke don't fix it..
