04 Silverado, 5.3Liter, A4
On "cold" cranking (coolant is less than 130 degrees), the engine cranks but immediately goes to anywhere between 2500 and 3000RPM. It hangs there for about 1-3 seconds before falling the the desired idle speed. Above about 130 degrees, I do not have this much of a problem (revs to only about 2000RPM, hangs for the 1-3 seconds, then falls).
What I have noticed is with the key on but the engine not running, the throttle is sitting at 16% (electronic throttle). When I start the engine, the throttle remains at this setting (16%) for the 1-3 seconds. It then drops down to anywhere between 5-10% (the required throttle setting to idle depending on coolant temps).
WHY is this happening? What dictates the cranking throttle setting? Attached is the current file.