I had my Diesel engine worked on recently. I had an oil leak from one of the fuel Injectors. The Mechanic only replaced the fuel injectors SEALS on the passenger side and changed out the fuel line. Ever since then my gas mileage has gone to crap. Should the fuel injectors have been replaced along with the seals? My engine is a 2014 Powerstroke 6.7. I’m not a engine guy so if this makes no since please feel free to let me know along with your advice regarding my poor gas mileage.