Yes, the ECU was reset. The battery voltage is 12.57 volts...

I've ordered a cheapo pressure gauge with a female schrader valve on it, and will then get clarity on the fuel pressure.

About 5 minutes.

All the motor mounts and torque bushings are OE rubber style (all replaced about a year ago). I unplugged the MAF, and of course immediately got a CEL and a MAF code, but the idle was about the same. I took some graphs driving (at normal engine temperature, 4th gear about 55 MPH, and 2,500 RPM) of t...

OK, thanks for the confirmation that I know just enough to be dangerous.

So what would be the recommendation for my next move?

Thanks!

Here's the STFT at idle:
And here's the STFT at 2,500 rpm:
X axis is time (samples, I think). Y axis is in FT in percentage.

Both look "good" to the untrained eye.

The new purge valve arrived today, and it has the same resistance as the old one, but unlike the old one, operates properly when energized. I installed it, thoroughly cleaned the spark plugs, and drained the power and did the relearn procedure on the ECU. The vibration at idle and shudder at shutdow...

Yes, I agree that that’s probably what’s going on. As a 25 year veteran of the IT Zoo, I can confirm that “If it can be done in software, it gets done in software”. My replacement purge valve is supposed to arrive on Thursday, and when it does, I’ll measure the resistance (recall: old one is 25 ohms...

Yes, I agree that Matt's sticker diagram is consistent with my car and (therefore) the diagram I drew of it — because the sticker diagram just says that the other end of the line goes to the fuel tank. Which it does. But while doing so it “tees off” to the vacuum input of the FPR under the rear pass...

Yes, there are 3 lines to my FPR, as expected and as described, and as depicted the the diagram I posted. But my snorkel has exactly 4 openings: MAF, throttle body, PCV, and IAC, and my MAF is attached directly to the airbox -- no intermediary snorkel. Here are some pictures showing all this. Front ...

Cool. FYI, my sticker is identical to the one posted by matthew1.