I bought a 2006 f350 6.0 diesel last December and have had the fuel injector module changed, egr fixed- both covered - but am having issue with hesitation and it stalling for a bit- changed air filter and both oil filters and seemed to get a little better but now the last week or so it seems like it's surging at stop lights or stalls- when I'm on the highway it seems ok but when I'm under 50 it is up and down