2017 Expedition XLT EL with 136k, no mods. I keep getting the stored code P1548:00-6C or P1548:00-68 engine air filter restriction. I’ve tried new air filters and cleaned and put the old one back in with no change. I’ve also cleaned the intake sensor and the map sensor. Smoked the tubes with no leaks. Cleared the codes with every change and it’s been going on for about 8 months now. Gas mileage goes down by 1 when it has the code. Am I missing something?