A few days before my ford ka doing the same problem and i do the same thing , clean therot and idle speed controller with a cleaner , ( which can clean oil , greece and carbon) and fix it again , but alas it,s not done , i mean remain the same and and Finally i do it was the FINAL TOUCH :)
" Is Lose Your Bettry,s Negative Lead off and remain it for 1 - 2 min and then fix it " and it,s DONE and now my Ford is Running fine ;) .
I am in germany and i ask for the idle speed controller price was 130 euro from a Ford Dealer
Zash, August 2008