Thank you for the reply M.B. Doc, I've been doing a lot of back-reading of old posts and found a thread from 2006 with exactly the same symptoms as mine.
http://www.peachparts.com/shopforum/showpost.php?p=1279905&postcount=23
May I ask where the throttle actuator and the OVP is located and how can I check them if they are bad?