Okay so I own a 2003 mazda protege5 straight drive and about 2 or 3 weeks ago it had started running really bad like it acted like it wasnt wanting to go or that it was trying to cut off whenever I would stop and right as it would take off. The check engine light has been on for a long time but now it was flashing. So we took it to an auto store and had them plug it up to the computer thing and it read that it had a misfire in cylinder 2 and that usually meant like spark plugs, an o2 sensor, or a coil pack. So we started with the spark plugs and that didn't work, almost seemed to make it worse. Then we put in 2 new o2 sensors the upstream and downstream still yet it didnt fix it but its seemed to help with when it idled it no longer acted like it wanted to cut off but when I put it into 1 gear it acts like its gonna cut off unless I have the rpms above 2 or 3ish when I let off the clutch. And it acts like it dont want to go or its sputtering and jerking and the rpms will randomly fall when going down the road even if I have the pedal to the floor. So all in all it was still running like crap. So today we were going to buy the coil packs because when looking online it had all the symptoms of a bad coil pack, but on the way home it started to run hot and it cut off so we coasted into a parking lot but it wouldn't start back. So we went ahead and put the new coil packs on and it still wont start. Somebody please help us because I'm at my end trying to fix this car in the last couple weeks. I just dont know what else to really do.

 

CAM position sensors are common to fail on these older cars.

 

what are those and are they expensive or hard to change

 

Price unknown, easy to replace.