do yourself a real favor and take the money you were going to spend on all these sensors that you are guessing at and buy a scanner instead... THEN you can actually buy the RIGHT part the first time and the time savings ALONE will make it worth while. it makes not a single whit of sense to shotgun a problem like this when you can actually know the answer for real this time and every OTHER time something happens.

I hear you, but a scan tool costs like $400 and I have to wait until the weekend to trouble shoot.
I'm going to stop buy Ocean Performance after work and spend $110 for an IAC and ECT. I should be able to change those 2 parts in about 1/2 hour.
If changing those parts does not work then maybe I'll invest in the scan tool.

i got mine on ebay for less than you are about to spend.

After dealing with this maddening problem for the better part of two years, I finally got off my butt and ordered a new IAC motor and TPS from BAM. Removed and cleaned the throttle body, installed the new parts and now the GD surging is gone. I have a 2007 GM 502 but the intake, etc. is from my 2000. If I were you I'd just order the IAC motor, clean the tb real good and install the new motor (2 screws, very simple) and I'll bet you'll be good to go.

Rock

I picked up an IAC and ECT tonight.
I'll let you all know how things turn out.
Thanks for the input!

Well guys I finally got out on the water to test after replacing the IAC and ECT.
She ran perfectly and idles at 600rpm in or out of gear.
Thanks for the help.