hello everyone, New guy here so don't be to rough, i recently bought a 2001 ford f150 5.4 screw 4x4, four days after being home i go start in in the morning about 45 degrees out, starts fine just after a little waiting it bogs down then revs up a few times, i've been doing some home working reading around (online) and first thing i've replaced was the Idle Air Control Valve, ran better but 2 days later it ran worse, took it to get diagnostic test and misfire out of cylinder 3, replaced the coil, so it has been running great for 3 more days now rough idle MAINLY when engine is cold, at idle and when in drive and foot on the brake waiting at a light. Check engine light came on, comes up with Bank 1 and Bank 2 system to lean, my guess is a vacuum leak?

Any ideas would be great Thanks, Tyler

 

I'd change the fuel filter if you haven't changed it yet. Maybe you got a bad tank of gas? check the simple stuff first.

 

It does sound like some sort of vacuum leak to me....I think you're probably on the right track.