Master or slave cylinder
 

Hey guys I have a problem thats been ongoing now for a couple months. I can drive it fine and usually shifts fine. Problem is sometimes it will have good pressure on the pedal all the time throughout the range of the pedal. Sometimes it won't get pressure until about a third of the way down. If I play with the pedal I can get full pressure again. When it doesn't have full pressure its hard to get into gear unless I'm rolling. Truck has 140k. Slave and clutch done at 67k. Original master cylinder.

Reads like you have some air in the system, also check under truck for leaking fluid.

Because of the Master cylinders angle air can get stuck at the top.

Remove cap on reservoir and remove the rubber insert
Add brake fluid so it is fairly full, do not put cap back on and do not touch the clutch pedal
get under the truck and open the bleeder on the Slave, 5/16 socket or wrench
This is called gravity bleeding
Let fluid run out and watch for bubbles
DO NOT let reservoir run dry, so close bleeder if you think it is getting low and you still see air bubbles coming out, then add more fluid to reservoir.

reseal the reservoir and drive truck.
If same pedal issue happens then you have air in the Master.

There are several videos and picture posts on how to remove and bleed the Master
Google: ranger clutch master cylinder bleeding

If there is fluid found on the outside of the master when removing it then it is leaking and should be replaced

No leaks and the system hasn't been touched since I did the slave at 67k. I popped the cap and the reservoir was full. I'm not sure how air could get into the system without any leaks. Is there such thing as a flush? I did notice the fluid wasn't the cleanest but I'm kinda afraid to touch the slave and have it go on me.