95 Villager idle problems

Here's what I have so far, the problem is the van starts up fine, then starts to stumble and stall. It does it when started cold. I pulled the CEL codes and the three codes are 32 EGR control solenoid, 33 O2 sensor, 34 knock sensor. I inspected and checked the operation of the EGR valve and solenoid and all seems fine. The van has 170k and the last tune up is unknown. So I repalced the cap & rotor, it has Bosch Platinum plugs and don't know if they are worn or not. I know the O2 sensor needs replaced but I don't think it should cause this new problem, because the sensor should of been replaced long time ago. I'm also leaning to replacing the spark plug wires because of unknown age. Any advice would be appreciated.
Tim

if you have doubt on last tune up, do one. it will only help. if there are codes stored, than there has been a malfunction with the ones you listed. the soliniod opens the egr when it is time to release gas frumes built up in the intake. if they dont get released or recycled it will cause a rough idle. the o2 and knock sen. will without a shadow of a doubt cause rough idle
as well. if van is storing these codes you need to take care of them, they are causing the problems.