After checking around the turbo components I found several problems. 1st - Turbo bypass valve vacuum hose was leaking at both ends. Repair by running length of brake like with two rubber hoses and zip ties. 2nd - breather at crankcase tower clogged, but flame trap is venting at the small vacuum hose. The thing is I just replaced the flame trap and tower 4 years ago. - repair by replacing. 3rd - hose connecting the inter-cooler to intake metal hose was torn underneath the clamp - repair by replacing. This should stop the O2 sensor from seeing extra oxygen due to fresh air entering the system and also blowing out under turbo pressure. thanks for the push in the right direction. It's been too hot to work on this car, since my shop already has another car on the lift. Now to just run the 740t for awhile and then set the AMM with the diagnostic light. I know from the other 4 turbo cars that I own, turbo need complete sealing in the system for any air leaks. Just glad it wasn't a burnt valve. Keep those bricks rolling! 96 Volvo 850t5 - 89 Volvo 740t - Volvo 58 444 (getting ready for the highway) 92 Sabb 900t - 87 Saab 9000t- Saab 91 900s - Saab 96 900s.