i have an 06 f150 5.4l 2wd. It runs fine when cold but once at operating temp when I slow down OR put it in reverse it starts to rough idle and sometimes stalls. I've changed vct solenoids. Cam positioning sensors. Plugs and coils. Throttle body. MAF sensor. And plan on changing the o2 sensors soon. This is an intermittent rough idle and I can get the truck to idle fine if i rev the truck up a little. It shows lean codes on bank 1 when this happens. My main question is can a vacuum leak cause intermittent rough idle that I can stop by revving it up in park. And does the 2wd 2006 have any vacuum hoses on the back of the motor by the firewall? Any other ideas to check. The dealership took my valve covers off and said my phasers and timing set are all in good shape and not causing this issue. What all can make this intermittent problem?