Alright, I finally got the codes off my EEC. My connector was different from the three that were referenced in one of the web pages you mentioned, but I did a little guess and check work trying to figure out which terminals to jump on my EEC connector. I was actually able to use the flashing of my check engine light to get codes (my repair book told me about this technique). Okay, so here are the codes. I counted the codes about three times to make sure I had things right. Regular Fault Codes: 335 Diagnosed Circuit: Differential pressure feedback EGR sensor Condition: Sensor output less than or greater than expected during Key On Engine Off test 539 Diagnosed Circuit: A/C Switch Condition: A/C on during Key On Engine Off test 565 Diagnosed Circuit: Purge solenoid valve Condition: Open or short Continuous memory codes: 214 Diagnosed Circuit: Camshaft position sensor Condition: Open or short 332 Diagnosed Circuit: Differential Pressure Feedback EGR sensor Condition: Insufficient EGR flow I should add a couple notes: My engine thermostat stuck closed one time and overheated and temporarily seized my engine while it was idling to warm up in a parking lot at work. This happened a couple years ago, and after the time I first brought my truck in for a diagnostic. I don't know if that could explain any additional fault codes. Also, I had my A/C system recharged this past summer. Before that, I had problems with my A/C pump clutch going off at random intervals causing my engine to rev in strange bursts. That might explain the A/C fault code. So, with that known, any new light on the issue? You can see that the cam sensor code did indeed show up. Would a bad cam sensor cause the EGR flow to fault as well? I'm not sure what the EGR does, I assume something related to exhaust quality or something. My thought: Bad cam sensor trips EGR fault, which in turn gives me bad emissions to fail the I/M test. I dunno, someone help me here.