The engine is EFI so the idle setting is computer generated. You'll need and engine programmer to change this setting.
According to Gates ( they manufacture timing belts etc ) the 2.5 liter engine used in a 1999 Ford Ranger is NOT an interference engine
The engine oil dipstick is on the drivers side of the 4.0 liter V6 engine in your 1999 Ford Ranger Helpfull
On a 1999 Ford Ranger , 4.0 liter V6 engine : The engine oil dipstick is on the drivers side of the engine
( 160 horsepower ) for the 4.0 liter OHV , V6 engine in a 1999 Ford Ranger
No , the 3.0 liter " Vulcan " V6 engine in a 1999 Ford Ranger is an ( Over Head Valve / pushrod design engine )
On your 1999 Ford Ranger , 4.0 liter EFI , V6 engine : I believe the EGR valve is just to the left of your engine oil dipstick ( when you look into the engine compartment from the drivers side ) The EGR valve is lower down and has a round shaped top
On a 1999 Ford Ranger : The engine size should be somewhere on the decals in the front of the engine compartment You either have the 2.5 liter four cylinder engine , the 3.0 liter V6 engine ( the engine oil filter is on the drivers side of the engine ) or the 4.0 liter V6 engine ( the engine oil filter is on the passenger side of the engine )
4.0 liter OHV - V6 , 3.0 liter - V6 , 2.3 liter - 4 cylinder
According to the 1999 Ford Ranger Owner Guide : With engine oil filter change : The 2.5 liter four cylinder engine and the 3.0 liter V6 engine take ( 4.5 U.S. quarts ) The 4.0 liter V6 engine takes ( 5.0 U.S. quarts )
On a Ford Ranger , 3.0 liter V6 engine : The engine oil filter is on the drivers side of the engine
According to the engine wiring schematic in my Chilton book : For a 1999 Ford Ranger , 4.0 liter EFI , V6 engine : ( there are 3 oxygen sensors )
According to the 1999 Ford Ranger Owner Guide : With engine oil filter change : The 2.5 liter four cylinder engine takes 4.3 liters / 4.5 U.S. quarts of (5W-30 engine oil )