2000 S is stalling...like it has narcolepsy

[steverw]

Hi, My 2000 Boxster S has started stalling. By that I mean that the engine just stops. No roughness or misfires, no thunking noise or feeling of a mechanical interference causing it it to stop, it just turns off. It's abrupt like the key was turned off. First time it happened was on the highway. I felt a stumble, but it kept running, feeling like when you push start something while rolling downhill, fed more gas to keep it going, but as soon as I came to a stop, the engine quit. Wouldn't start, towed it. Next day it starts, runs some minutes, then stops. There is no rough running, and I can restart it once or twice, but after that it won't catch. But after a few hours it will start again. I have a durametric tool, wondering what to look at. Battery is OK, cranks fine, just doesn't catch.

Yes, i have had codes 0133, 0153, 1275, 1276. But these predate this stalling by quite some time. The codes point to emissions issues, and need to be addressed, but could they cause these abrupt stalls?

I have not done anything prior to these stalls, like changing air filter, etc. I did change the oil some months ago.

Thinking it could be fuel issue, I bought a fuel filter, looks easy enough to replace. But I don't like to take chances by running it much without some better idea of what could be wrong.

I'm new to this kind of diagnosis. I have had only an air oil separator failure in the 8 years and 130K miles I have had it, and the two precat O2 sensors. Would appreciate advice.