I'm no expert but I've posted a similar question about a year ago and all the feedback was (and all auto manuals support this) that a clogged cat presents itself at higher rpm when the engine needs to exhaust more and can't.
I had the sluggish/delay in acceleration from a standing start. Mine was a combination of an erratic fuel pump and a bad radiator which caused the motor to run a little warm which the computer compensated for by altering the timing to cool the motor which severely affected performance.
Hope I offered more insight than confusion.
P.S. The CD rom was very useful BTW. If you don't have one and want a fair alternative. Try one of the popular mechanics version which offers most of the data in a much easier to use format. But you can't replace the original for the amount of info.