06 ford e250

Oxygen sensors will not affect vacuum operation, seems like that was a waste of resources. The other thing is that when you replace perfectly good parts with possible inferior parts, you could actually introduce problems you never had. This is why diagnostic testing before replacing parts is so urgent. If you replaced the EGR valve, did you also clear out the EGR passages on your 13 year old van which would almost assuredly be coked with carbon deposits? Lastly, I would seek out a disconnected vacuum hose / component vacuum leak either under the hood or under the dash.