Wow, that's a lot of questions.LOL. The cat was changed because changing both O2 sensors didn't do anything to fix the problem. The codes are P0131 and P0137 one for each sensor. I seem to get better mileage with the light on than when it is off. I have checked the cat, sensors and wiring and everything looks ok. Today I am going to remove the O2 sensors and see if they heat up as they should. I will also do continuity tests on the wires as well as remove and clean every ground connection on the inside of the fenders. Yhis will be difficult as I have never been able to buy a manual for this car. I did buy a couple of CDROM manuals that won't load on my computer so I do not have a good wiring diagram. I was able to find one for a 1995 960 but it only has one O2 sensor as far as I can see. I am going to order a factory gas cap and if all this doesn't work I think I am going to offer it to a charity on condition that it must go to a crusher and I get to push the button! The car may be posessed and I have dubbed her Christine as in Stephan King's movie and book. LOL. This will undoubtedly be the last Volvo I will ever own!