I have a 94 850 turbo. It ran fairly well up until two months ago. I replaced the Camshaft position sensor the rear Oyxgen sensor, and now I'm getting an overboost code. This wouldn't be a problem except the car won't rev past 4000 rpms without the fuel cut off stepping in. The boost hasn't been tampered with, so it's at stock level. I installed a maual boost gauge to see what was going on, and for a while both gauges showed the same movement. But now, the car's gauge sometimes shows normal full boost even if I'm just crusing, while the manual gauge will show maybe 1 lb. I rounded a corner the other night, and could feel the fuel cut off, while I could hear the wastegate blowing off boost, and the car's gauge was straight up, between the black and the white. I'm trying to figure out what the ECU reads to determine boost, and is there a sensor that might be bad, and how do I check it. The dealer was no help. The tech wasn't sure how the ECU read the boost.

Brian