5.7 with 47K codes P171p upon warm-up and then p171 & 174p next warm-up

Thanks. I have done all the simple things. So did the dealer. I used propane to check for leaks and they did it with a vacuum gauge. The IAC valve seems to be an interesting thought. I am still waiting for a PCV valve from NAPA, but I think it is not the problem since everyone has to order it. This is a garaged truck that is only driven once a week or so, so I also bought some good injector cleaner thinking that may be an issue. It is definitely not anything as simple as an air leak or dirty filter. I will pull the IAC valve off and clean it and then if that does not help it looks like I will hang another MAF sensor on it. It has to be something that is sending a lean signal to the control module. hmmm

fuel pressure test?if starving for fuel sometimes,PO171-PO174 will set.i think on your truck everything is in the tank pump,strainer,filter,reservoir,sender,and regulator filter/strainer could be clogged and pump still trying to work?