Hello Michael,
If your vehicle has a lot of miles on it, it could be the EGR valve, not opening and closing properly. Over time carbon builts up internally,some models have a diaphragm in them and works up and down on a shaft inside the unit, I've cleaned this in the past, remove and disassemble (usually not complicated to do), and either clean gasket and/or replace it. Other systems. have only a solenoid or two, which can also become restricted with carbon. This is worth a check, EGR problems can have symptoms as lack of power, if
EGRs can set computer codes also, if you have access to a Code Reader this may help also.
Hope this helps,
In Christ,
walt, October 2008
