Hello everybody I have a 2001 Honda Accord LX with the 2.3l Engine in it. Complaint: With Engine Warmed up the idle surges from (1350 RPM - 1460 RPM) with Active Diagnostic Code P0505. Here are the steps I have taken to troubleshoot code. Step #1 Topped off Coolant & Burped (NO CHANGE) . Step #2 Installed a NEW IACV (NO CHANGE) Step #3 Swapped out the throttle body / IACV port is clean (NO CHANGE) Step #4 Checked for Vacuum Leaks using carb clean and yes engine was warmed up, sprayed all vacuum lines and around the intake manifold gasket area's (NO CHANGE IN ENGINE SPEED) & Couldn't hear any vacuum leaks hissing either. Step #5 Changed EGR Valve & Gasket (NO CHANGE). Step #6 Installed NEW Coolant Sensor (NO CHANGE). Step #7 Started up car (Engine Cold) held Accelerator @ 3000 RPM til engine warmed up & cooling fans came on, let car idle & accessories OFF and recorded the RPM'S (1350 RPM - 1460 RPM) / Next I plugged the IACV inlet port on the throttle body with my finger and recorded the RPM'S (720 RPM - 725 RPM), Idle is now in spec with port plugged / According to my Haynes Manual I need to attempt to adjust idle speed. Step #8 Pulled small plug off throttle body to adjust the idle speed screw, I found loosening screw counter clockwise caused higher more irractic idle & clockwise lowered the idle, but unfortunately mine was turned all the way in and my idle speed could not be adjusted any further. STEP #9 According to my Haynes Manual if the Idle Speed could not be adjusted the IACV is probably the culprit, but I already changed mine with (NO CHANGE IN PERFORMANCE). Step #10 Next I checked the IACV Connector and wiring harness NOTE: Connector seemed kinda loose on IACV just the littlest amount of play back and forth but seems to be making contact. I didn't see anything out of the ordinary with the visual inspection on the wiring harness. Step #11 Disconnected the IACV connector & turned ignition keyswitch "ON" tested voltage between Pin #2 & Body ground, Voltage equaled battery voltage or 12VDC. Step #12 Next I checked continuity between pin #1 of the IACV harness connector and body ground, My result was good continuity 0.00 Ohms Step #13 disconnected negative battery terminal of the car then disconnected the ECM/PCM Connector that contains the IACV Control / Aux Wire. Next I checked the continuity between the control wire colored black/blue & body ground. Result: No Continuity. Step #14 Next I connected a a jumper wire between pins #3 of the IACV connector harness and body ground. I then went back to the ECM & checked continuity between the IACV control wire black/blue & body ground. Result : GOOD continuity 0.00 Ohms. Step #15 Reconnected IACV connector to the IACV / Reconnected Negative cable of battery & turned the ignition switch "ON" and measured voltage between body ground & IACV control wire black/blue. Result: I had voltage present 11 VDC. According the troubleshooting procedure next step is to change PCM/ECM out with known GOOD PCM/ECM. Does anyone agree that I should move ahead with that? Also NOTE I ordered a NEW IACV harness connector as well so when that comes I could put that on as well even though the pins didn't look to bad, my only concern was the slight amount of slop the connector had it doesn't stay 100% tight, but it does lock in. Any advice is much appreciated, thanks!