Here's an update after changing the EVAP purge valve yesterday afternoon:

Last night I drove ~30 miles / ~45 mins through the city with a mix of traffic lights and max speed of 50 (no highway speeds). I didn't observe any rough idle or issues, but I wasn't really observing that with any consistency with the bad purge valve either. While driving around, I monitored the STFTs and LTFTs as follows:

Idle:
LTFT B1: 5.5%
LTFT B2: 10.2%
STFT B1: -3%
STFT B2: -3%

1500 RPM while holding speed and RPMs:
LTFT B1: 2.3%
LTFT B2: 7.0%
STFT B1: -0.8%
STFT B2: -2.3%

2500 RPM while holding speed and RPMs:
LTFT B1: 0%
LTFT B2: 1.5%
STFT B1: 0%
STFT B2: -1.5%

Any RPM (1500-2500) while foot off the gas and not holding speed while letting the car coast:

LTFT B1: 5.5%
LTFT B2: 10.2%
STFT B1: -3%
STFT B2: -3%

I assumed the LTFTs would continue to get better with driving, but that wasn't the case today. This afternoon I drove the same route as last night (up to 50 mpg) for about 30 miles. The LTFTs were a little worse today:

Idle:
LTFT B1: 7.1%
LTFT B2: 11.72%
STFT B1: -3%
STFT B2: -3%

Under load while accelerating or holding speed (~1500-2500 RPM)

LTFT B1: 0%
LTFT B2: 4.0%
STFT B1: 0%
STFT B2: 00%

Cruising speed at ~1200-1800 RPM with foot off the gas while letting the car coast:

LTFT B1: 7.1%
LTFT B2: 11.72%
STFT B1: -1%
STFT B2: -1%

I came home and built a DIY smoke tester and did a smoke test for about an hour connected to the front of the intake and then to the rear of the intake. I found no intake leaks. Are these lean LTFTs concerning?

My interpretation is that I'm running lean more at idle than under load. That would suggest that it's more like a vacuum leak at idle and probably not the fuel injectors since I'm not lean under load. I would assume a weak fuel pump would exhibit poorer performance under load, too. Is it possible for a weak fuel pump to manifest issues at idle but not under load? What about a faulty O2 sensor associated with the aft bank? What would you all check next?

 

The fuel trims dropped immensely after replacing the purge valve. Your total fuel trim (STFT & LTFT) are within range.

 

I've driven over 500 miles, about 1/3 of them at interstate speeds. The CEL has not reset itself. LTFTs are still around 7 and 12 for banks 1 and 2, respectively. I can still see the idle stumble occasionally while in park and while stopped at a light.

All O2 sensor outputs are essentially identical except long term secondary O2 sensor fuel trim where bank1 is 0% and bank 2 is -0.781%.

I've run a tank of Techron injector cleaner. Evap valve was OEM.

Can anyone confirm that the lack of CEL reset indicates a lingering issue? Any other suggestions?

 

You should reset the CEL from the getgo.