97 ford expedition rough idle 5.4
for the past two weeks my 97 ford expedition 5.4 has been running with a rough idle, on cold starts she will run perfect untill she warms up, once the truck warms up it will idle rough at stop lights or when stopped , when driving it will run perfect, untill i stop at a traffic light.
things i have tried so far,
brought the truck to auto zone, they put it on there scanner and she spit out two codes " PO171 & PO174 " the guy sad these two codes meant my MAFS " mass air flow sensor " was no good, i replaced the " MAFS " two times , and the truck still ran with a rough idle after she warmed up.
the next day i brought the truck back to auto zone for one more test, the same codes cam back, he now said , it was my O2 sensors , i then replaced all 4 o2 sensors, this did nothing for my rough idle.
the same night i asked a friend for advice he recommended i change my " EGR valve" i changed the " EGR " and this did not help.
the next day i decided to have the fuel injectors cleaned, & changed the fuel filter ,this also did nothing for my rough idle.
at this point i am in the hole for some big $$$ and i am also lost on what to do or try next... any advice would be greatly appreciated.