Toyota Repair: 98 Camry, 6 cyl, cat/O2 sensor/rack n pinion replacements, voltage waveforms, sludge problem

Question
Ted,

1998 Camry V6, XLE, 165,000. Got new engine at 144K for sludge problem, new tranny 2 yrs earlier. Toyota messed up radiator and nicked boot on rack n pinion at engine replacement. Bought new assembly and want to install.  Read your response to 94 replacement for R&P. Curious about steering alignment and counting threads for tie rods to be aligned properly.  2nd'ly have P0420 Cat Bnk 1 error and P1411 2nd'ary air injection incorrect downstrm flow detected errors.  Suspect Cat but heard many complaints or all 4 O2 sensors needing replaced, plus EGR valve?  Any suggestions?   Also had coil pack go out and suspect another one is going.  Other than age- what would cause the frequent demise of these ~$110 items?  Want to weld new cat in for other one.  Have MIG should be able to do.  What about narrowing down O2 sensor error and P1411 error.  Not looking forward to the knuckle breaking on the R&P but already have the rebuilt- just need the courage and maybe liquid courage and some nerve with warmer weather.  Inside of tires wore out in less than 20k miles.
Thanks much,  Jim   sorry allot of questions but appreciate your consideration.

Answer
The p1411 code refers to the EGR position sensor, it's located directly on top of the EGR valve, replacing it will take care of that code. The 420 code is normally only related to the converter but the O2 sensor operation should be retested after the cat is replaced. The best way to do that is with a diagnostic scantool that has the capability of showing the o2 sensor voltage waveforms on the display.