Join Date: Oct 2007
Location: Buenos Aires-Argentina
Seems that you definitely have a problem in the throttle bodies. You might have an air entrance below the lower butterflies causing the engine to rev up. You have to have a close look at everything around, looking for something loose or a cut air hose or something.
If the secondaries servo motor would be bad you´ll probably get an FI code. This one executes the fast idle via a linkage to the lower (main) butterflies shaft during cold operation.
I insist to take a look at the temperature at the very moment that the problem occurs. The temp sensor might have an intermitent failure.