Mitsubishi Repair: service engine light, acceleration problems, o2 sensors

Question
I had a continual service engone light problem. They yave replaced both o2 sensors and catalytic convertor. 3 months later, Light on again - same code: P0304  Cylinder 4 Misfire Detected.  Had sparks changed approx. 10,000 mi, 9 mos. ago. only maintenance might be needed - new battery : 2003 Mitsubishi lancer 73,000 miles.   since i don't have  alot of confidence with dealer, figured might as well try new battery. have been acceleration problems while driving, entering traffic, etc.

Answer
Kasey: Got an AutoZone close by? They will code your car for free and then reset your computer if that engine light is still on. You have to reset the computer because other wise it does not know you have fixed things. Acceleration problems could your fuel pump is not putting out enough fuel. These newer cars you are never to let the car get down below 1/4 tank of fuel. Because your fuel is what cools your fuel pump, if you go below that amount to much with time you can burn out your fuel pump. Might be also that you need a good tune up. That might work wonders with the acceleration too. Hope this helps and good luck!