Long time since i've been here but the old wagon has been good. Well maintained incl new o2 sensors and maf 6 mos ago. New plugs 2 yrs ago. New pcv.system and silicone vac hoses 2 yrs ago. Valves done 3 years ago so I assume head gasket done too.

Was climbing a hill against wind with thule cargo box on top. Cruise was on so max boost as the speed control attempted to keep speed up. Then lambda light came on and car now idles rough, and not great mileage. Of course at start of holiday and far from my code reader. Car not blowing any strange smoke. Oil just changed and not looking cloudy. Antifreeze looking darker than I remember but its been a while since checked. Can't see any oil floating in it

Any thoughts would be very appreciated. Is this my head gasket?

Thanks in advance for the help

Perry