Everytime I push the clutch in the truck redlines, unplug the rear speed sensor on the dif and it fixed it, and yes I already replaced that sensor in the dif.

 

Welcome to the forum

What year and what engine in your Ranger?

 

It’s a 2000 ford ranger with a 2.5L

 

So it idles OK, 750-800rpms when stopped, clutch pedal up or down?
So no air leaks

1998-2000 Rangers used the rear axle ABS sensor for speedometer/odometer and computer, also cruise if so equipped
So unplugging the rear ABS sensor means you unplugged the speedometer/computer from a speed signal

The speed signal was part of the emissions system on manual trans vehicles
When above 5MPH the RPMs should hold when clutch pedal is pushed down, but not go up, after 5 to 7 seconds of holding pedal down, the RPMs should drop to about 1,000rpms, and hold there until speedometer is under 5MPH and then RPMs will drop to idle, 750-800

So in the absence of an air leak it reads like a computer issue
Unhook one battery cable for 5 min
Reconnect, this resets computer

Also try cleaning the IAC Valve, make sure its a Motorcraft brand, or Hitachi, if previous owner replaced IAC Valve with a 3rd party brand that may be the issue

 

The truck always had issues with idling up and down, I just replaced the iac last night and have no issues with anymore. I will try the battery.