Further idle diagnosis....

[Roadster]

So I been having this slight idle problem since January. More annoying than an actual problem. But something I can live with for now...

As mentioned in another thread when I start the engine (has Marc's chip) if revs high for a few seconds and then come down to 650-700 r's at idle. Driving out of the development and stopping along the way, the idle comes back down to the 650-700 range. Now when on the road going through the gears and then coming to a complete stop the idle can sometimes be around 900-1000 r's. Now what I don't understand is that with my foot on the brake and I let up on the clutch pedal, I can get the engine to drop to the lower rpm range and stay there. On further stops it can be a hit or miss situation on where the idle will be, unless I use the same procedure as mentioned.

Talking to Yun, as he mentioned it could be the shaft in the throttle body that may be worn. Also did the airhorn test and used the FSM as my block in front of the airhorn. At high idle 900-1000 r's after blocking the airhorn, the idle came down to normal after about 3-4 seconds. And on Marc's site it also mentions the problems with the TB. So a lot to absorb.
I also cleaned (sprayed) the outside throttle springs and whatever part of the shaft I could get to with WD40. Amazing the amount of grime that ended up on the paper towels. I also sprayed lightly inside the TB, even though it isn't recommended per Marc's papers. Didn't really matter, because it acts the same. I always start off with a normal idle and even revving the engine to around 1500-2000 rpm's the engine will come back down to normal. Now when driving, it is a different result.
Hooked up the Tech 1 on a warm engine and the IAC was reading about 20 with normal driving. Backing off in 3rd gear @ 2000 r's, the IAC would be much higher and fluctuate at higher readings. Come to a complete stop whether the idle is normal or higher, reading has always been "0".
From Marc's site:
"When the IAC goes to zero the idle speed can not be reduced by the engine control system. Then the engine idles at more than 650 rpm." What I don't understand is when the idle is normal, I still get the "0" IAC reading when stopped.

TPS is set @.54v And the throttle stop screw is adjusted correctly. The throttle cable has play, so it isn't too tight that it would hold the throttle off of the idle stop. I changed the IAC from before, but it did not make a difference. I need to verify that the IAC fully closes as per Marc's papers.
Other then the above the engine runs great especially with the secondaries fully operational.

So short of sending out the unit to Marc for a rebuild, guess I will keeping trying to find an easier if possible fix...