pro tip, include the transmission so we don't have to go hunt down which possibility it might be
from the tech articles, I gather that it could only be the Mazda M50D-R1 , is that correct?
Model Trans Code P/N Vehicle Speed Ratios Mitsubishi FM132 D 1988-1992 2.9L 2WD 5-Speed Unknown Mitsubishi FM145 D E67A-7003-FA 1985-1987 Ranger 4X4 5-Speed 1st: 3.769 2nd: 2.210 3rd: 1.516 4th: 1.00 5th: 0.812 Reverse: 3.400 Mitsubishi FM146 D 1988-1992 2.9L Ranger 4X4 … Continued
www.therangerstation.com
If that is the case, I have to ask, the slave cylinder is the most well known weak link... quote from that same page:
"
The hydraulic clutch, slave cylinder/throwout bearing is another item you should pay close attention to. After time, the slave cylinder fails to release the clutch completely. If you are having trouble shifting into 1st and reverse while stationary or if your truck creeps forward with the clutch pedal depressed the slave cylinder/throwout bearing is probably at fault. Unfortunately there is no easy fix here as the transmission must be removed to replace the combination slave cylinder and throwout bearing.
"
In your parts list you don't mention a new slave cylinder, just the slave pressure plate.... so just for verification, you did not put a new slave in it? (being the weakest link I plan on replacing it every time I have to do a clutch or otherwise open up the bellhousing/clutch area).
If you didn't replace it, my first guess would be the slave cylinder itself.
What was the symptoms that made you put all the parts into you have so far?