My wifes 2006 Expedition has a bad bog on medium to hard accel. Even has a pop or backfire sometimes into intake. No codes and no CEL! Dealer kept it for 2 days and told us the infamous, "we can't duplicate the problem!" Told us it my be a plug dropping out but not sure!!
"It's not a miss" I told them, I want to get this fixed before my extended warranty goes out!
It has about 80000 miles on it, they talked me into a fuel filter but that didn't change anything. I'm thinking fuel pump????
Runs great except on harder acceleration.
Any ideas??

 

A lean condition can cause this to happen. I'd start by looking for vacuum leaks, especially where the PCV hose goes back and connects to the intake manifold. Then I'd get a pressure tester on the fuel rail to confirm the fuel pump PSI output.