2003 mazda 6 2.3 engine. won't stay idle , runs rough Installed new cam shaft sensor, 4 spark plugs, installed new coil , checked cam timing and car still only runs on 2 & 3 cylinder. Can anybody help with my problem. The car has 220,000 KM's and I bought it used from a guy, There are no CEL's on the computer.

 

No, can't help you!
Not enough info. Year, engine, mileage.
Any history of maintenance?
How long has this been going on?
Any Engine Codes from engine light flashing on dash?

 

The car has 220,000 KM's and I bought it used from a guy, There are no CEL's on the computer. No history of Maintenance, Only thing that has been changed was the oil.

 

Driving around too long with a car like that will plug up your cartalytic converters.
Before doing any work disconnect the negative terminal of the battery followed bya depression of the brake pedal.
DO THE FOLLOWING since you don't know it's history:
1) Change all ign coils and check connections
2) Clean the throttle body
3) Clean the MAF Sensor
4) Change the PCV valve
5) Check vaccuum leaks especially on accordian intake tube before throttle body
You can temporarily fix with Duct Tape
6) Clean EGR valve
7) I would also add a ground from engine block to negative terminal
Re attach negative terminal, let car idle for 10 minutes. Drive for 50 miles as re-learning is begun. Also put in fuel system cleaner.

 

Check that all your injectors are working, use a screw driver to listen.

 

How do you know its firing on only #2 & #3? Are all 4 exhaust ports hot or just those 2?