Now I've got the INFAMOUS P0505 Code:
 

As the title states got this code yesterday. After doing some research on the ORG today, here's how I plan to attack this.

It's a 2000 Max/GLE auto/Cali emissions
- disconnected engine mount connectors today.
- gonna remove and check to see if ECU is burned out, if not then I'll just replace the IACV and go from there. Priced it @ ARCH for 234.00
- if the ECU board is fried then I guess I need both an ECU an the IACV plus a reprogram for the keys.

I started this thread to document the progress and hopefully it'll help someone as previous threads have help me. If anyone as anything to add that they feel will be helpful, please feel free.

Okay so here's an update: I removed the computer, opened it and saw it was good. Here are the pics: http://i7.photobucket.com/albums/y26...3/IMAG0182.jpg
http://i7.photobucket.com/albums/y26...3/IMAG0181.jpg

I removed the IACV and it was definitely shot. It leaking internally and it had the rear of the throttle body 'gummed up' pretty badly. So I replaced the valve, throttle body gasket while I was in there and cleaned it up. Put everything back, cleared the code and fired it up. It started up perfectly and idles settled around 845rpm. I'm not too sure if that's still a shade too high but it seems okay to me. After about 120miles the code comes back but the idle has surged or anything. I'm now out of options, except for checking the harness itself but I don't have any symptoms. Any suggestions are welcomed.