I had this problem and I was posting in another thread, but I can't find it. I have an 01 job 1
I had the same codes, I replaced the MAF, code went away, but it warmed up at the same time.
Next time the temp dropped below 50 almost 8 months later, I got the same codes. I looked for this elbow that everyone else was talking about. The 01 Job 1 does not have this same elbow. We replaced the O2 sensors, cleaned the IAC and nothing worked.
Then EUREKA!!! Or just dumb luck
While my husband was working on the IAC, he was spraying carb cleaner and the engine almost died. He figured out that my upper and lower manifold gaskets were probably the problem. While he had the IAC off he shot some carb cleaner at the manifolds and the truck almost died.
Sure enough when we pulled it apart, the gaskets were shredded, they were just paper, or cardboard or something. Replaced them, reset the code, and I have been good for over a month. And I swear the truck runs a lot better since that. We just went through a cold snap too, where it was dropping down in the 30's at night and it starts up, and runs like a champ.
