2002 Volkswagen Jetta ECM problem, or some other systemic s

I've been in a discussion with my mechanic about my 2001 VW Jetta VR6. The Jetta has been running rough at low speed and idle. First indication that this might be a more serious problem occurred when check engine light began blinking during periods of more rapid acceleration. The light went back off and then came back on to stay (solid- not blinking) a couple weeks ago. It continued to blink occasionally during periods of rapid acceleration, but would go back to the solid light afterwards.

The mechanic initially thought that I had bad ECM, recommending a computer replacement. I called him today and he said based on a conversation with some other specialists, he's no longer sure it's the computer. I got him to give me the codes. Here they are:

17832- Secondary air injector system bank 1 P1424
16684- Misfire P0300
16686- Cylinder 2 mis-fire P0302
16804- Catalyst system cylinder bank 1 operation too low P0420 intermittent
16795- Secondary air injection faulty flow P0411 intermittent
18011- ECU defective P1603 intermittent

Yeeeesh! What do you guys think is causing all of this? Any ideas? I'm putting out a call for all of your collective wisdom and brainpower to help me figure out the best way to proceed.