There is only one coolant temperature sensor on a 1999 Ford E150 6 cylinder. The sensor is on the front of the engine just below the valve cover.
The fuel pressure regulator on a 1999 Ford E150 Van is located near the carburetor in the engine compartment. It is to the right and in front of the carburetor.
How do I replace the heater core in a 1999 Ford e150 conversion van
4 - 8 3 - 7 2 - 6 1 - 5 front
On a 1999 Ford E-150 , 5.4 liter V8 engine : 4 - 8 3 - 7 2 - 6 1 - 5 front of vehicle
Usually on passenger side farthest cylinder towards the back of the vehicle
Rear right side of engine in cylinder head.
4 - 8 3 - 7 2 - 6 1 - 5 front
Check your underhood sticker, it will have that information.
on the right side of the engine
It is located behind the battery on the wall. You must remove the battery and the battery tray to gain access. It is held in with two 5/16 screws.
The number one cylinder on a Ford E150 2001 with a 4.2 coil is on the left, just behind the fan. The firing order for this engine is 1, 4, 3, 5, 3, 6.