I've a question
 

I've a maxima with 241,000 miles on it and it run fantastic expect when it's idle. When it's idle it act like it wanna stall out but it don't. Last time I let it idle for a long time, I got the p0171 and p0174 code and the mechanic can't find the problem. What can it be? Any help would be greatly appreciated. Thanks

You have a vacuum leak. Either plenum, or behind the maf, or the hose running behind the engine along the firewall (my choice) that connects to the pcv valve.

Thanks ill check

Dirty TB? Partially stuck open, ever so slightly?

How would I know that it's partially stuck open?

x2

https://cimg9.ibsrv.net/gimg/maxima....eed49675bf.jpg
They're saying my lean code is coming from this. Could this be true?

mine ripped off the same, so I used electrical tape and wrapped the heel out of it.

quite possible you could get a code.

tape up, clear code and see….

Agreed! It is downstream of the maf so very likely the source of your issue!

Update: the lean code "I think" is coming from air coming through the spark plug hole..My valve cover was leaking and cylinder 4 spark plug seal was damaged and oil was on my spark plug. I changed BOTH valve covers, all seals, OEM ignition coils and spark plugs. Then I changed the oil and she runs like a champ again. Thanks.

Glad to see you got it worked out. I am doing this same work on my 2012 this weekend. I’ve never done anything like this before, but after reading the info posted on these forums and watching way more YouTube videos than I ever thought I would on the topic, I feel pretty confident with taking it on and just working slowly. Was there a specific guide or video you referenced? Anything unexpected you ran into while doing the work?