thx for all the info and other guys too...will do it one by one....lots of $$ @_@i'd say 15 is better for neo .
the lowered look and the lighter rim gives u a lot more power and better look as well :)
and change ur extractor to 4-2-1 .
and please be reminded when u buy a 2nd hand car, always go for standard maintenance at least .
best if u could spare some for top overhaul or even better, full overhaul :)
do like others said, check spark plug, air filter, clean throttle body, change 4-2-1, change to 15"
and i believe u could restore ur system.
Don't forget to reset ur ECU .