Need help!

[Richw001]

Okey, A friend has a 1999 Chevy Suburban with a very rough idle. It has the throttle body and it is a 5.7

The truck is showing these codes: P0131 bank 1 sensor, P0171 lean bank 1, P0135 o2 heater circut bank 1 sensor 1, P0300 misfire, P1133 fuel and air.

He changed the plug wires, plugs, pcv, throttle position sensor, EGR, put sea foam in the fuel tank, sprayed gm throttle body choke cleaner in the intake.

And truck still runs the same.

 

Also, sprayed carb cleaner all around intake looking for leaks and no changes in idle at all.

 

Note: when he removed the plugs all four on the drivers side were covered with thick black carbon, and passenger side were normal.

 

 

Any help at all will be greatyl appriciated.

Rich