I have a 04 Optima with the 2.4L. When I bought it, it was misfiring. Replaced the coils and plugs. Found out that the timing belt jumped a couple of teeth. Took it to a local shop and had the timing belt and other components replaced and when I went to pick it up it lost complete power. The shop was beating around the bush with trying to figure out what was wrong, so i brought it back home. When I brought it back home, there was times when it wouldn't even stay running. Some people saying it is the fuel pump/filter but when I took off the fuel line at the rail when I tried starting it, it was spitting out fuel fine. After that, I could start it and it would run fine but when I step on the gas pedal, it acts like it wants to die. I can get the RPMs up to roughly 2k and any further it dies out. I am in need of help because its the wife's car and she wants to drive it again.