Just to provide some updates:
I lubricated throttle linkage twice, it helped a little but not much, Yesterday I cleaned the throttle body by spraying throttle body cleaner into the throttle body (I did avoid spraying onto the mass air flow sensor), afte that, haha!! the petal became so light that I have to use extra force to lift my foot from the pedal now.
Guess after these 3 months of exercise, I must have a really heavy lead foot and have to get used to the extra light gas petal now
