super rich fuel mixture

Hi, I have a 90 Passat with the 2.0L DOHC and recently installed a K&N OE replacement filter wich did wonders for fuel
economy and performance but then i had issues with my cateletyc converter. I wanted to get a little more performance out of
it so my dad and I tokk the cat out emptied all the baffles so it is completely hollow now and then we put it back on. i noticed a
drop in fuel econemy but the car was running fine and it sounded great and it did just what i wanted it to do with
performance.

now for the issue, ive noticed with winter coming as the temp drops below 50 F the car is idling super high and not dropping
until i drive for 20 minutes or so ive also notice my fuel econemy plumit. ive checked the plugs and they show small amounts of
carbon deposites and a strong smell of fuel. my exaust also smell very rich.

so i was wondering if i opened the system up to much or i forgot to adjust something for the more open system.

-- thanks in advance