Why a bad oxygen sensor code
 

I have a 2001 A4 1.8T 74,000 miles. I recently replaced both O2 sensors & the MAF. My CEL came on this morning. The code is a P0130 - Sensor 1 Bank 1.

My car was stalling last night and had a rough idle. Can someone please tell me why I'm getting a bad oxygen sensor code when I just replaced it 2 months ago?

Did you use Bosch O2 sensors? Also check for vac leaks.

Yes I did use the Bosch OEM sensors from the dealer.
My cam seals and gaskets are leaking.
Could that be allowing air into the system?

Well you can replace the cam and crank seals when you do your timing belt. When was the last time that was done? Should do it every 80K miles or so, so at 74K have it done soon. ECS Tuning sells the Ultimate Timing Belt Kit w/ everything from coolant, w/p, timing belt, tensioner, crank seal, cam seal, t-stat, and all the other belts too. Just do it soon. What other gaskets are leaking?

Check the part number of the pre-cat O2 and make sure it's the right one for your car. There is a VIN split in 2001.

Also, what are the O2 sensor readings?