I'll get the name of the stuff I use

 

Additives don't solve problems though, they just cover them up............

 

Adukart is right, should only be used as a temporary fix really. Not bad to run injector cleaner either just to make sure everything is clean. The stuff I use is from CRC. Says guarenteed to pass emissions, which I doubt but it seemed to make a difference in how mine runs. I use it every 3,000 miles

 

P0138- O2 Oxygen Sensor Circuit High Voltage (Bank1, Sensor2)
P0420- Catalyst System Efficiency Below Threshold (Bank 1)

Replace the downstream O2 sensor and you should be find as far as the MIL goes and might fix your pinging problem, but pinging is when pre-detonation occurs and I would pull one of the plugs to see what it looks like, you may have a fouled plug causing your problem...