Yep, those late 80's early 90's Ranger clutches were a nightmare to bleed.
I worked at a trans shop and we did lots of them.
Can't tell you how many times we "thought" we had it bled..... called the customer to come get it.... and....
Customer pays and gets in his truck and the clutch pedal just falls to the floor. No clutch action.
Very embarrassing.
We learned that once we thought we had it bled and it worked fine on the road test.
DON'T call the customer as soon as it's "done"...
Put it in the shop and let it sit overnight and check it again the next day.
Inevitably it would need just one more bleed. OR
Sometimes... just a couple pumps of the pedal and it would be fine.
Later we rigged a little 12V electric pump with a container of brake fluid, (aftermarket windshield washer reservoir and pump)
and pumped the fluid in from the bleeder screw. It works surprisingly good.
Think about it....
Air rises in fluid, so pumping the fluid in from the bottom pushes the air up and out the master.
It's messy but it works.
One and done.
Oh, drain the system completely first, "then" inject the fluid in from the bottom until the master reservoir is full.
There used to be a tool sold for this very purpose.
I think it was called the Phoenix Injector.
Basically a hand pump with a reservoir to hold the fluid.
Fittings for all the various bleed screws.
Same idea just a manual pump.
Edit;
We would "always" replace BOTH slave and master on any clutch job on these trucks.
Actually on any clutch job that had hydraulics, no matter what make it was,
but esp on the Rangers.
If it's time for a clutch, the master and slave are not long for this world anyways.
No matter how good they seemed to work before.