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Just looking for expert opinions on how to approach all this. I'm trouble shooting through. Any mechanic I've talked with around here thus far is 100+ just to look at and unfortunately no one I can really trust.

Background
Car stalls when pressing the accelerator at a stop. Happens at stop signs, red lights, after switching gears from revering from a parking spot. The key thing is it stops when I press on the accelerator pedal. It doesn't just stop while idle. The car stalls specifically when I press on the gas peddle and only from when the car is moving 0 mph thankfully. It hasn't stopped while I'm in the middle of driving thankfully.

To give some more background here. This was happening a while ago and I came across a suggestion to turn off the "econ mode" which I did, and the problem went away for a while. Now it's back and happening every so frequently. Moreso now the "check emmission system" light is coming on. It doesn't always come on when I run the car, say about 50% of the time (this became a much larger issue in the past few days with heavily increased stalls as well as the light).

I went to a local auto store for the code reader and it generated P0171 which is "system too lean".
things I've done so far.

put in a "tune up in a can"
put in "heet"
did a visual inspection of hoses but per the other topic pertaining to this stalling I will take off the mass airflow hose (tube?) to get a better inspection. I can't imagine what would make it crack but I guess that sort of thing can happen right?

I was going to check the spark plugs but didn't bother yet as multiple people told me if that was the issue I would have recieved other error codes, not sure that's entirely true. Those readers are not right 100% of the time. I have experience with it missing a code completely on another car. Either way the mass airflow should be easier to remove and inspect than the process of going through and inspecting spark plugs. I mean .....I can do a visual inspection of spark plugs, measure the gaps even . But ultimately couldn't a plug be bad without being able to see it? Maybe I'm wrong. The idle is smooth and not rough most if not all of the time.

Gas cap loose....seen many times. Thing is the cap is not loose. However and this is a question most anyone who owns this car could answer for me. Is there supposed to be a flap where the gas pump goes? I could have sworn there was a flap there and now there is no flap. Once the gap cap is off it's just an open hole to the gas tank. I'm not sure if there should be a flap there.
-pertaining to this my mechanic friends say even if it broke off the fact that it is not there should not be the reason for a stall. However it made me think ...what if it's in there and blocking the flow of fuel from the tank. So if anyone could at least let me know if there should be a metal flap there that would be wonderful. Not sure what I am to do if there should be one.


Long story short I'm trying to trouble shoot through this as I'm on a budget at this second and any little bit saved helps quite a bit. So Thanks to those who help.

 
Rep Power: 367

https://www.obd-codes.com/p0171

 
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indeed, could you advise if the entry to your fuel tank has a "flap" or whatever it would be called?

 
Rep Power: 367

as you can see, I have a 2002, very different from your 2015...

 
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indeed question is for anyone though. I seem to recall a flap being there. If it fell in I wonder if this is the problem

 
Rep Power: 222

Primary o2 sensor is probably bad. Use only OEM (Denso/ntk)

 
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Hello,

I was wondering if you were able to figure out what was causing the car to stall? I have the same car with the same issue. It started stalling last year during the summer. The dipstick was constantly popping off, so I got a new one from the dealership, had a transmission flush, turned the eco system off, but continues to stall. At this point I’m not sure if I should keep the car or get rid of it.