Power loss...... My alh engined 2000 jetta has less power than before

[MukGyver]

Hi Mukgyver.
I have a hand held infrared thermometer. So I point it at the intake side of the Cat....and then the exit...? WHat should the temps be... >
I imagine a normal one would be equal, and a plugged one will show higher temps on engine side, compared to exhaust side >>

yes, if the outlet side is not at least 50 degrees higher that's a good indication it's not functioning right. You would expect to see the outlet side significantly lower if your cat is plugged.

edit: make sure engine is up to temp