Ford F-250 Problem Report
Ford F-250 EGR orfice in intake may plug with carbon
The EGR orifices in the intake manifold may plug with sludge. If the truck has high mileage, this may cause engine misfire when first accelerating because too much EGR gas is directed into the cylinders of the unplugged orifices. This makes the mixture lean, which causes a gradual stumble that increases in severity until repaired.