Thanks for reading my post!

I've got a 1979 Ford F-100 Custom - with an L6 - 300 cid (4.9L) engine. It is 2WD and has a standard cab and man-power steering.

Long story short, after a relative used a mechanic who is prone to big goofs some funny things started happening. The mechanic IS an expert and I am not, but he is forgetful. Among the funny things, there is clearly a part missing. It looks like it is related to the vacuum system or emissions system, possibly a vacuum check valve, a ported vacuum switch, or something completely different. It does not have an original hood so there are no diagrams under there.
It does have some symptoms I'm hoping are related:
1) rough idle (it dies and seems to be running lean but this is getting worse as the days go on so probably not just a carb adjustment?)
2) It recently stopped taking gas. The line to the tank fills up with gas and shuts off the pump. I can squirt in 0.03 gal every 9 seconds. This led me to think that maybe one of the hoses is involved with venting the gas tank.
I'll let my pics and video do the talking. I tried to point it out clearly.


You probably wanna see my body.



Just a quick view of the engine compartment to orient you if you need it.


The arrows point to three hoses that are just flopping around and should probably be connected to something. The green-tipped hose goes to the PCV valve. (Yes I know it needs a new intake tube.)


One of the two filtered hoses leads here.

The other filtered hose leads here.

Someone's degreaser (probably mine) washed away the labels on the crank case long ago.

Except this label which is either immune to degreaser or someone wisely avoided spraying it.

Here is the video!
Short story long, this was my Grandpa's farm truck. The first vehicle I drove on public roads. It was my daily driver in college but I had enough with its poor gas mileage, parallel parking, and frequent issues that I did a swap with my parents. I've moved on to other cars, but in the video I say I borrowed it from my parents to help move. They are the "relative" I mentioned.