It could posibly be a bad transmission mount or a universal joint on the drive shaft or even maybe loose torque converter bolts
Sway bar bushings
Motorcraft MERCON automatic transmission fluid is used in a 2001 Ford Ranger 5 speed manual transmission ( yes - ATF )
According to the 2001 Ford Ranger Owner Guide : Motorcraft MERCON automatic transmission fluid is used in the 5 speed manual transmission
Motorcraft MERCON automatic transmission fluid is used in the power steering in a 2001 Ford Ranger
According to the 2001 Ford Ranger Owner Guide : Motorcraft MERCON-V automatic transmission fluid ( see if the type used is engraved in the dipstick to confirm )
Motorcraft MERCON automatic transmission fluid for the 5 speed manual - YES ATF ! Motorcraft MERCON V - ATF for all the automatic transmissions in a 2001 Ford Ranger
In a 2001 Ford Ranger the automatic transmission fluid requirements will be indicated on the automatic transmission fluid dipstick or the handle ( Motorcraft MERCON - V according to the Owner Guide )
I'm not a mechanic / technician but the automatic transmissions on a 2001 Ford Ranger would be electronically controlled , so there wouldn't be a modulator valve
Sounds like the transmission
A bad transmission.
I believe the neutral safety switch is mounted on the side of your transmission
The reset button for a 2001 Ford Ranger with a 4.0L engine and automatic transmission is typically located on the transmission itself, near the transmission pan. It may also be found on the driver's side, just above the transmission oil pan. If you're having trouble locating it, refer to the owner's manual for specific diagrams and locations.