Can anyone please tell me what this is?
 

I am new to this forum so I apologize ahead of time if I have posted this incorrectly. Here is a little back story on what is going on I have a 2004 F150 Lariat 5.4 with 224k miles on it throwing a P0174 trouble code, which from what I have read is a fairly common and lets say robust trouble code with this particular year F150. Luck me right!

Here is what I have done so far:
Replaced the MAF, upstream O2 sensor, all coil packs and spark plugs, and a smoke test, radiator flush, and fresh oil and filter (I know some of this maintenance wasn't necessary for this particular code but with the miles I wanted to giver her a bit of a tune up while I was at it, and I included non-necessary items for full disclosure and help in troubleshooting)

I have not been able to find a vacuum leak so far, smoke test was negative but then I saw this little guy, circled in yellow, just hanging out not connected to anything. When I take the cap off I can hear the engine sucking air so I know its part of the vacuum line but I am not sure exactly what it is or if it is supposed to be connected to anything on the other end. As you can see in the photos it is located on the passenger side and appears to connect to the back of the intake manifold or maybe a little further down I am not sure. I have done a visual scan under the computer and behind the battery and have not been able to find anything that may connect to it. Doesn't mean its not there may just mean I don't know what I am looking for. Could someone please enlighten me as to what it is that I am looking at and if it actually connects to anything or if I am barking up the wrong tree.

I know there are a ton of possibilities with this code ranging from vacuum issues all the way to the fuel pump going bad or even a blocked cat but I am hoping to easily diagnose and fix it myself, while I am NO mechanic I can use the hell out of YouTube lol. I don't currently have an OBD reader that has live data on it so I can not check fuel trim levels at this time. I know this would greatly help me narrow down my diagnosis so I am thinking that will most likely be my next troubleshooting purchase but in the mean time any and all assistance would be greatly appreciated. Thank you

Not sure here. I did get a pic of mine but doesnt look like i have that one.

What year is yours?

Oh I should also add that at around 40-50 mph I get a bit of a stutter like it’s bogging down but if I raise the RPM with a little extra press on the gas pedal it starts running normally again which seems to go along with the lean condition.

Just to be on the safe side I’ve ordered a new air filter and a new fuel filter. Again maybe not necessary for this trouble code but still general maintenance that should help with the overall health of my truck.

Reading some of the sticky’s on this forum I shall be checking the foam seal on my air filter holder deal to see if that also needs replacing.

Have I mentioned that this particular trouble code sucks pretty hardcore because it’s very non-descriptive in nature. Lol.

That looks like the vacuum line for IWE system 4WD... if you have 2WD they cap it off.

X2.

That makes total sense since it appears to just be capped off, and if that is true it is not likely relate to my P0174 code. Seems like to troubleshoot this further I will need to get myself an OBD2 scanner with live data.

So having said that any recommendations on a decent scan tool under $50 that will get me what I am looking for, also anyone have a opinion on the Bluetooth/wifi app driven scan tools? Are they worth anything at all and would they provide me the information I am needing in order to try and narrow down my search? I am interested of course because price point on some of these makes them quite attractive but if they only report codes they are worthless to me.

Any experiences and advice you guys have to share would be greatly appreciated. I have been looking on amazon for a few days reading descriptions and reviews but that's getting to be like information overload because it seems there are as many different scan tool options as there are makes and models of vehicles since the creation of vehicles. Please point me in a direction that keeps my wallet happy and helps me to track down this snipe I am hunting.

So I did a little maintenance this afternoon, pulled the air filter and inspected the tray and the foam gasket around it was crumbled and worn down to the plastic so I replaced the gasket with some high durability rubber foam tape with a touch of extra spray adhesive just for good measure and did a full adaptive memory reset to purge all the previous short term and long term fuel trim data. While I am only 10 miles in this is the longest I have been able to keep the light off lol!! going to celebrate the small victories for now. Here's hoping this fix was just that easy I will let you guys know any updates to come. Thanks to all that have chimed in thus far its greatly appreciated.

Nice..

Well unfortunately the light came back on today but hey its progress its taking longer and longer to come back on. I will need to bite the bullet and get on OBD2 scanner with live data so I can track fuel trims and what not so I know my next direction. This particular code is a pretty big pain in the ass since its fairly non-descriptive as to what the issue truly is.

So I need some feedback ladies and gentlemen. I want a decent weekend warrior OBD scan tool (I'm no mechanic but I like to figure out my own repairs) that will provide me with live data. Please let me know some advice on which direction to go when buying one, I'd like to stay below $50 for the tool/software.

Those of us who have experience with both classic readers and the newer Bluetooth/wifi app driven readers which is better and why?

Seems to me that if you can get all of the same info via app that would be the way to go but like I said I am not experienced in this at all so please chime in and let me know what you think and why.