Last night my 2003 A4 has a flashing check engine light when I could stop smelled that stinky smell like it was the catalytic converter. Is it the "cat" and what might cause this?

 

how was power in the car? Greatly diminishing? What sounds was the motor making, exhaust wise, and under the hood?

 

yes, power greatly diminished, engine sputtering, also when hood was opened, looked like either the manifold, or the "cat" was cherry red "glowing" it was evening and it looked like there was a light on under the hood...

 

is there an after market catalytic converter or is it strictly a dealer item?

 

LEAN CONDITION! Get it checked out ASAP. Something is causing a severly lean mixture condition to exist greatly increasing the exhaust temps. This is very bad and will melt pistons, valves, etc. Get the codes read now.

 

I doubt this is lean condition. This is a typical plugged catalytic converter. Change out your 'cat'! One way to check for sure is too check the tailpipe when the engine is running (don't run it too long, that getting so hot is hard on it!) and get down by the tailpipe and see if exhaust is free flowing, or if it sounds muffled or plugged.