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.
Here's how the throttle body gets dirty. When an engine shuts down, hot exhaust gases and unburned fuel float to the top of the engine. As the vapors bake from the engine heat, they form black sooty carbon deposits inside the throttle body. Follow the plastic duct from the air filter housing up to the throttle body. Remove the duct and locate the throttle cables and rotating mechanism. Rotate the throttle mechanism and spray the cleaning solvent around the inside of the throttle body. Give it a moment to work and then wipe out the crud.