Ive got:
UK MY97
Full Decat
ITG Panel Filter
Forge VTA Dump Valve
Dawes set at 1 bar
Knocklink & AFR

It is running really rich the majority of the time except when I have been on the motorway at 80-90mph for a while. When I come off the motorway and boot it I am getting Amber and a flicker of red on the AFR (ok/lean). It is not showing any knock on the Knocklink.

Could this be a symptom of a failing/faulty Lambda Sensor getting too hot and degrading the signal? Would it be worth changing this just to be sure? If so, do I have to get one from Subaru or is there a cheaper third party alternative?

Thanks

Terry