Try going somewhere that you can have the code pulled (AutoZone, Advance Auto Parts, etc.). They usually read the codes for free and they can tell you what the code is to diagnose the problem. If you car smells bad, and I had to guess, I'd say your high flow cat is bad.

You can always have the code cleared and see if it happens again. You can also try putting your stock parts back on to see if the problem goes away. You may need to get a new high flow cat or an o2 sensor, but you won't know until you pinpoint the problem.