This problem I'm having is slowly getting worse, I've also noticed the colder it is the worse it is. I though in the beginning I might need new coils, but I read somewhere on here the intake manifold gaskets could be bad and cause this as well as vaccuum leaks. I uploaded a vid to YouTube maybe one of the pros on here can help me narrow this down. This is my only family vehicle and I need it to run good for my wife and child.
The truck is a 2000 5.4 4x4 Scab

 

It sounds cammed... What exhaust are you running on it? I assume it doesn't have any internal engine modifications such as cams? What are the RPMs doing?

 

I wish I knew what your fuel trims were. Does it feel like a misfire when it switches to od around 45?

 

Could it be valve covers leaking oil into the plug wells?

 

No internal mods at all, exhaust is just all 4 cats with the muffler removed from a magnaflow cat back system.

Here's the kicker, when I'm in gear driving it runs smooth as glass all the time. Only a couple times it has done that while in gear. When I put it in park it will go back to the loping sometimes.

The valve covers do show signs of leaking but it's pretty small, it's not running down the block and nothing in my driveway.

 

I'd guess it's not an oil leak issue then. I wonder... Could the fuel pump cause it to lope like that? We have an 01 expedition in my family that's had the fuel pump replaced like 2-3 times now. I don't remember it loping like that though. I wanna say the PCV valve developed a leak in a hose one time that caused a rough idle. Might be worth checking into. Well, that threw a code... Hmmmmm... It's really odd there's no codes being thrown. How often does it lope like that?

 

My black truck did something very similar and it turned out to be coil or two that ended up shorting in the boots. I also had to do my intake gasket but not for the same reason.

 

It does this every time I start it or put it into park. Less when the engine is warm but still there. Colder weather def affects it.

 

That's exactly how my truck sounds (except mine is a 4.2) and I have the p0171 and p0174 codes. I suspect it is the intake manifold gasket. I've replaced the pcv valve, the valve elbow, cleaned the MAF, and replaced the fuel filter and it still throws those codes and sounds just like your truck.

 

Looks like a lean issue on both banks, sounds like intake manifold gaskets to me. I'm not sure there's a test for that aside from replacing the gasket and hoping it goes away. Shouldn't be too difficult to do I wouldn't think.