7.3 has a miss??

[mtcarmelfarm]

A friend of mine has an '00 7.3 dually. It wasn't running right and the check engine light kept coming on, so his mechanic told him it needed injectors, which they replaced. He said it helped and the light doesn't come on anymore. But between 45 and 50 it starts missing/running rough, if he hits the tow haul button or shifts out of O-Drive, it smooths right out??????
Any ideas? He has a tuner, but they unhooked it when the did the injectors.