Here are the additional numbers...

15 MPH rpm is 1857 %CO2 is 13.8 %O2 is 1.4

25 MPH rpm is 1883 %CO2 is 13.8 %O2 is 1.2

also, today I bought a vacuum pump, got the truck up to operating temp. put the vacuum line on one nipple on the egr, pumped and and got nothing....put it on the other nipple and pumped it up to 10 and the truck began to stumble and almost die, never quit though but idled very rough, slowly the vacuum blead off and the engine returned to it's normal idle. Noahwins said to give it one pump, when I did that no vacuum registered on the gauge on the pump, I had to pump it several times to get the needle to register...gonna try Camoit's suggestion and smother the carb with a rag and see if we can discover any hidden leaks...