i have a 1999.5 f250sd 194,000 miles. my truck ever sense i put the rebuilt turbo in and up pipe gaskets im getting 13.2 mpg empty no trailer. i dont have a heavy foot. and i dont let the rpm usually get above 2200 rpms. i recently have cleaned my airraid air filter and changed the fuel filter. nothing seems to help. i dont hear any boost leaks anywere and my boost gauge reads up to 25 psi what should i check im stumped.