It is usually located on the outside of the intake manafold and is centered on the throttle... (the flap that pivots to let air into the combustion chambers). The throttle is located on the inside of the manafold... and cannot be seen. The switch is usually mounted on an elliptical or rectangular flat plate with a screw at the right end and another at the left end. The plate can be rotated slightly by loosening the screws. This adjustment sets the minimum and maximum throttle opening and tells the computer what the throttle is doing. Suggest you do not mess with it unlesss you know what you are doing.
1993 190E 2.3
2000 Toyota 4x4 Tundra