Okay here is my problem. I have a Ford Focus 2003 2.0L SPI engine and I got a check engine light on. When my friend put the scanner, I got four codes. P0507, P0300,P0304,P0171. I really dont know what to do anymore because I changed the manifold, the whole catalytic converter and the muffler. On top of that, when Im driving at 40mph, my car starts to jerk(skip) a little. That happens everytime I hit 40 mph but once Im at 50mph it stops skipping. What should I do? What do each code mean?
Please help me out.
Added (1). Oh and I just cleaned the Mass Air Flow sensor and the air filter.
Read more: What should I do? P0507, P0300,P0304,P0171?
