Hey guys, I have had an ongoing investigation with my pickup and I am just about to the end of my resources as well as my patience. I have had the error codes 171 and 174 since I bought the truck, and have finally resolved 171, but 174 is now accompanied by 1507, 1409, 1121, 300, and 443. I have already replaced the EGR valve, (which I believe took care of 171), PCV valve, IAC valve, and have checked all vacuum lines for any signs of air leaks. About a month ago, when I started the truck it did not go into high idle right away, and runs very rough. After replacing said parts, I am suspicious of the problem being either the TPS, or possibly even a baad ECM, although I am not sure how to diagnose. Could there be one root problem causing all of the issues that I am having? After I replaced the EGR valve, i thought that she was starting to run better, and after driving around for a bit without manually clearing the MIL, it went off all on its own and I rejoiced for all of about a day, when the light came back on with a goodie basket full of codes. Any input would be helpful, as I have had about enough of the green monster..