Ford F150 - Engine idling rough and stalling

Hey ya'll! This is my first post because you guys normally answer my questions if I dig deep enough in the forums, but this time I'm befuddled. I have a 2003 f-150 with a 4.6 160k miles. The engine had a miss at highway speed the other day and I figured another COP had given up the ghost. No check engine light, but I've had this three times before (dealership replaced them before, but I wasn't paying $380 again) and felt confident I recognized the symptoms. I decided to change all of the COP's and the plugs. After doing this my truck is idling extremely rough and will stall. I used Accel COP's (cheapest I could find) and Autolite plugs gapped to .054. I double checked all of the vacuum hoses and connections and all looks good. Why in the world would it start running worse? Still no check engine light either. Please help!

Well, I figured it out...It was a vacuum line. The ol' girl is running great now.

I've had a couple of messages about this issue so I'll clarify here. What I found when I went back under the hood was the breather hose on the right side valve cover had popped off behind the throttle body. It's difficult to see 'cause it's tucked under the cowling. With that hose off, I'm surprised my truck even started, much less got any kind of an idle. Well, I hope that helps!