Not sure how much info to give and still stay brief. 99 Sonata 2.4 4cyl Bought about 1 year ago. Had check engine light: Code was for bank 1 lean. Car ran fine. Reset light - stayed out for a day or two. Several months later performance began deteriorating until car choked out and died eventually replaced catalytic converter; much improved but some hesitation hesitation continues especailly when cold; when was car has trouble upshifting and is especially unresponsive around 2000 rpm If I floor is it will shift but when I let speed/rpm drop to 2000 or so it wants to bog down. Someone has suggested O2 sensors. HELP!!!! Thanks in advance.
