Stall and massive fuel consumption

[Curryair]

Today on my 5 mile trip from work to home my 2006 A4 2.0T sucked down a 1/4 tank of gas and stalled. The stall happened towards the end of the trip as I was making a right hand turn. Everything seemed fine until I down shifted to 3rd and let the clutch out in the turn. The throttle was unresponsive and the engine seemed to bog down. I down shifted to 2nd with the same result, so I engaged the clutch and coasted into a parking lot where it promptly died. I poked around under the hood for a minute and didn't see or smell anything out of the ordinary. Then I started it up and everything seemed fine again. It was then that I noticed that the gas gauge read significantly lower than when I left work.
Once I got home I opened up the engine compartment but still could not find anything. Even a spirited test drive failed to give any clues.

Should I be worried? I never smelled or saw a fuel leak, but I doubt the engine burned that much gas (about 4 gallons) in 4 miles.

Not sure if it is relevant but a couple days ago I replaced the thermostat and did a coolant flush and fill with G12. I also replaced the serpentine and installed a new K&N air filter. The PCV has thrown a CEL in the past but currently seems fine.

Hope someone out there has some ideas.

[kegobeer]

It might be the fuel gauge sending unit or maybe the gauge itself. You can test the gauges using vagcom. When I bought my car I quickly found out the gauge wasn't acting right, and it turned out to be a combination of the sending unit and the low pressure fuel pump throwing codes.

[seanj130]

I am thinking it may be one of the O2 sensors. I forget which one went bad when I started sucking fuel like a MOFO.. I feel like it was the primary one.

[Curryair]

I think you have it Keg. Long story short the next day I had the typical PCV codes pop up, so I replaced with the newer "p" revision and breather from ECS. Now I have the P0089 code and my fuel gauge is actually reading 3/4 with the tank full. Looks like I'll be pulling the back seats *ugh*. Is it wise to replace the in tank pump at the same time just so it's done?

[Curryair]

Finally got my fuel filter and low fuel pressure controller p/n 4F0906093K. Installed both. All my codes are clear and gone for over 100 miles but my gauge is still reading 1/4 tank low. Guess I'll be pulling the LPFP/sender next. Dumped some nasty brown fuel out of my filter so I have a feeling I could have just replace that to clear the codes. Car is definitely running smoother now.