Very good post. Not to hog the post but my sons 2001 was bought from a previous owner with a swapped 4.7 year not known. Wiring lacked needed 2 more o2 sensors [codes] I had a harness from a 1999 and paid for the swap of wires. Solved the o2 codes, but have had a persistent 0505 code, which is needed cleared for emission passing. Changed it out with 3 but still have the code, My question, possible PCM issue because of swap. Wiring chks out fine no issues. Sure could use some help. What in the vin# indicates 4.0 or 4.7, wondering what engine came out. Thanks.