Odd Stalling Problem

Over the last few days, I've experienced an odd stalling problem with my 05 Legacy GT.

It started Wednesday afternoon.

I ran the car through a car wash and let it idle while I vacuumed it out.

Then I pulled out on to the highway and sat at a red light for about a min... and the engine sputtered and stalled..

I immediately attempted to restart the car and it acted as if it was flooded... It would turn over and fire, but it would not sustain combustion...

I am pretty sure that it is getting adequate fuel since it backfired a time or two...

So I called AAA for a tow... After I got off the phone with them, I figured I'd try to start it again... It fired right up with no hesitation... I drove further north on 31...

Got to another traffic light.... it sputtered and stalled again....

Another 3 min wait, and it fires back up... This happened a few more times until I got to a parking lot and drove around and couldn't reproduce it...

I then called AAA back and canceled my tow request.

By this time my wife had met up with me and we ate dinner... After dinner I went to Chevron to get some more fuel (I thought that I might have some water in the fuel and my low fuel light was on anyway).

It stalled right as I pulled into the gas station...

After I fueled up, it cranked right up and I had no problems on the drive home.

Thursday the car had no problems on my 20ish mile round trip to work...

Friday afternoon, the car stalled about 1 mile from my house... Again I let it sit for 3 or so mins and it fired right up...

It just happened again this morning right around the block from my house... again it fired up after 3 mins, but would not immediately restart.

More details:

It always happens off throttle when I'm either coasting out of gear or idling at a stop. Bliping the throttle has never recovered it from a stall, and there have been a few times where before it stalled completely, it acted as if it was running on 2 or 3 cylinders....

60k miles and I almost always get my fuel at Costco.

Mods:

ECU reflash, headers/up/down pipe.. TMIC. Sealed Air/Oil Seperator system.

NO CEL