I have been getting a P1075 code for months now...rich bank. The vtm4 light & check engine light will both come on at times, while other times it's only the engine light. I have changed the map sensor, EGR valve, & replaced plugs & installed new iridium's. The light comes on & goes off sporadically now. It can be off for days...and then just come on again.

But...each time the light comes on, I can go fill up with 93 octane & it will go off. I have put in Techron fuel system cleaner twice. I also replaced 2 upper end O2 sensors as well.

Does anyone have any suggestions?

Thanks