rollerdr

I have a 1997 Suburban K1500 5.7 with 174,000miles and the check engine light is on. Transmission has less than 10K on it. I've been reading on this forum since I bought it last week looking for advise but I can't seam to find anyone with the exact issues I have all in the same case. I'm hopping the combination of symptoms and codes will ring a bell with someone here and you can tell me what repair to try first.

P0430 Catalyst Sys Efficiency Below Thresh (Bank 2)
P1406 EGR Valve Pintle Pos Cir.
P0141 Sensor Heater Circ (Bank 1, Sensor 2

The previous owner told me that the check engine light has been on since it had 68,000miles on it and that the garage told him that it would not affect the operation of the engine. At idle the truck runs ever so slightly rough between 500 and 600 RPM. While driving it feels great. But then again this is my wife's kid hauler and I drive a truck with over 240,000miles on it that was not well taken care of most of it's life but hell it was free. What I'm saying is I might not know how the 5.7 Vortec is supposed to run with operating normally.

My QUESTION is. Do I replace the O2 sensors? Is there a way to test them before purchasing a replacements. OR do I need to replace the catalytic converters with what I'm finding out is a whole new system involving two catalyitics and new pipes off the headers. If i have to go to that dual Cat system I assume there are places to hook up more o2 sensors fo before and behind the cat?

Is the P1406 ERG related to this issue?

I'd love to hear what you would do first and what to look for while doing it. Thanks for the advise in advance.