My truck doesn't run very often - maybe once every couple of weeks. Last time I went to drive it, there was a hole in a boot-like component behind the engine making a suction noise, but when I tried to cover it, it killed the engine. Any idea what this part is? This is a 2003 f-150 v8 - 4.6L I believe

 

Follow the hose back from the engine - where does it go?

 

PCV hoses and PCV heater connections

 

I'd go with the infamous PCV hose elbow but, given the lack of detail and no photo, that is subject to revision.

 

That's why I asked what I did.

 

Y'all are so fast!! I think maybe a video of what's going on could possibly help, so I took a quick one. Does this help?
It also has 2 codes - P0171 and P0174

 

Vacuum leaks usually cause those codes.

Post back AFTER you fix that giant sucking vacuum leak.

 

Follow the tube from the PCV valve to the back of the engine. Just before it goes into the intake, there's a rubber elbow. I'm betting the elbow has rotted away and is full of holes.

https://www.rockauto.com/en/moreinfo...=11784&jsn=929