I have been trying to figure out my idle problem all week. I just replaced my timing belt this past weekend. I have had it apart twice now to verify that I have all the timing marks lined up correctly. The truck runs just fine it is just the idle takes time to drop between each shift and when I come to a stop it idles about 1100 RPMs. I have cleaned the connectors and put dielectric grease on the IAC, TPS, and MAF. I still have the same issue. I also took the IAC valve out and cleaned it. I checked the resistance in it and reads 10ohms. I was going to try to check the voltage on the wire but I can't get my leads into it. I will have to try some wires then touch my leads to it. I can start my truck and unplug the IAC and it does nothing to the idle. I can unplug the MAF and it about stalls. I have a check engine light on with P1506 = Idle Air Contol System Over Speed Error. Should I replace the IAC? I am not sure what the sympthoms of a bad IAC are. Also, the week before I replace the timing belt my check engine light came on with the P1506 but it went away. Thanks in advance.