Code 31 and 22 keep coming on

Okay, I have a really annoying problem that I just cannot figure out. I have been getting codes 31 and 22. We took it through emissions and it failed horribly. So we got an obd1 ran the codes and replaced the EGR sensor and map sensor we also got a new O2 sensor PCV sensor and a new EGR valve. We replaced the spark plugs got a new fuel pump and filter checked all the lines to make sure there was no vacuum leak and when we were all done the truck ran smooth. We took it through emissions and it passed with flying colors the truck ran like a dream then about three days ago the check engine light came back on and it started running rough again and the same two codes are popping back up. We replaced the whole system and its still reading the codes we even checked the new parts to make sure they weren't defected. Now here is the part that is messing with us we went outside to turn it on this morning and the check engine light was off the truck was running smooth we drove it all day with no problems went to turn it off. A few minutes later we turn it back on and the truck started running rough again the check engine light back on and the same two codes popped back up. I have no idea what else to do. The last thing I can think of is carbon build up but I am not sure. Is there anyone who might know what the problem is your suggestions would be very helpful at this point? Also, sorry for the long message.