Yes, I'm extremely doubtful based on experience that this is only an EGR tube. The hole typically doesn't get that large and while it can contribute to P0171 it's not usually the only issue.
I'm a bit of an advanced person for this code. Got this code on a 97 Bonneville years back. Went through everything more than once. Smoke tested and all, there was no vacuum leak. A big thing that people do is they don't read up on the code. This is the rear O2 reading lean exhaust and the pcm counter acting that. However it reached a point that the PCM is commanded to tell you that the fuel trim is excessive.
On the Bonnie, the end result was I found out about those EGR tubes. I had new gaskets on everything, throttle body was super clean, maf was triple checked and replaced to ensure it was good..........and it ended up being corroded battery cables. If you pull the bolt that holds your cable to the battery and slide the plastic cover up over it.. if you see green corrosion embedded in the strands etc, then you will want to fix it and that can cause the issue. Also bad grounds for the sensor can cause the issue. But ... most of the time, it's going to be a vacuum leak or failing maf.
