I've been dealing with this P0171 issue for a while. Searched the internet and pretty sure its either replacing/cleaning the MAF? or its a Vacuum Leak. I took it to a mechanic who apparently did a smoke test and told me the below picture that these 2 parts needed to be replaced (and he would go from there). I replaced the check valve..and still getting the error. The other a Tee (tri valve) thingy. He also said that part wasn't supposed to be there and another valve was supposed to go there but I'm not sure he is correct as I've done plenty of research?

So in my own DIY efforts I took the bottom hose off that check valve and hooked another tube through it and with a cigarette blew smoke down it and low and behold smoke came out of the area in the picture below with the arrows (my beautiful artwork) in the direction it was coming out. I also took another wide picture below showing the areas I'm focused on here as in most research I've found there are just way closeups and no one every shows where exactly it is lol.

I'm pretty sure the vacuum leak is a good place to start as I see smoke however I have no idea whats under there and would like some advice on what I should be buying and needing a mechanic or my self to replace?

Thank you so much in advance!