[jackass#1]

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.