Release the Cancel button once the LED lights come on. This resets both the printer and the NVRAM together. Press and hold the Reset button near the back of a 5P or 6P printer as you turn on the power. Holding it for less than 20 seconds resets the printer only.
Once the throttle body is exposed, spray the throttle-body cleaner inside the air duct, and use the brushes to gently dislodge the dirt, gum and varnish that are present. Note: Be very careful not to let the thin, plastic spray nozzle (or anything else!) fall into the throttle-body opening.
A throttle body is essentially a large air valve that sits between the intake manifold and air intake pipe. Generally speaking, an engine has one throttle body, which bolts to the intake manifold's plenum (the large air cavity in the center).