97 suburban with multiple misfires

I have a 97 suburban (Vortec) showing multiple random cylinder misfires and running very rough. Problems started with codes for oxygen sensors (after the catalytic converter) not functioning correctly although at the time the engine was running well. Took me a couple of weeks to get to the sensors and by that time the whole engine was running very rough. I changed both post catalytic converter oxygen sensors. I also changed distributor cap and rotor, plugs, and wires. It is still running very rough and showing random, multiple cylinder misfires. Any suggestions? Thanks!

I had a '97 k1500 that did a similar thing, but mine was only until it warmed up, the problem was the coolant temp sensor. Another thing that you could look at, is the cat's themselfs, have a back pressure test done to see if they are plugged.

Any other codes?
You need to check out the miss fire.
Have you got a good engine capable scanner?
Most of them will give a reading on what cylinder and how many miss fires it has.
What kind of spark plugs did you put in it.
Other things to check with a mis fire is fuel pressure ,maf sensor ,and camshaft retaard setting and EGR valve sticking.
Also run a injector balance test.