Assuming there are no error codes. My next thought maybe the EGR valve is sticking.Assuming there are no error codes. My next thought maybe the EGR valve is sticking.
Don't forget that at least one or more of the fuel injectors could be dirty, or you have a compression problem on one or more cylinders. if you are still having a problem, try a top rated fuel system cleaner.
Answers & Comments
Could it be as simple as spark plugs and wires need updated/cleaned?
Assuming there are no error codes. My next thought maybe the EGR valve is sticking.
Don't forget that at least one or more of the fuel injectors could be dirty, or you have a compression problem on one or more cylinders. if you are still having a problem, try a top rated fuel system cleaner.
Check for vacuum leaks around intake. At that age hides can crack and split.