How To Clean Throttle Body
On a Volvo 850, you will see a black plastic cover with a single torx screw holding it down. Unscrew, remove plastic. You will now see the intake, the throttle body and the throttle wheel. Disconnect the intake from the throttle body. At this point, you have two options. You can use an O2 sensor friendly throttle body/carb cleaner, or remove it, and clean with the same thing. It helps to use a toothbrush to scrub the unbelievable amounts of oil blowby, varnish, gum, carbon deposits, etc. Reinstall other parts. Takes about 30 minutes from start to finish.