89 ranger manual trans slipping already replace clutch and slave cylinder? still slipping any help?

Clutch & pressure plate assy complete replaced ? Same size? Was flywheel turned, or at least roughed up? Slave cylinder have any adjustment on it, maybe too tight. Is there any play between slave & clutch fork assy?

Manual transmissions do not slip ie. when the gears mesh, there is no slip unless they strip out and make an awful noise and will not pull henceforth.

You probably still have a slipping clutch plate against the flywheel. You need to adjust the clutch petal linkage shaft to allow the pressure plate to be release from the thrust bearing, ie shorten the shaft length.. If you and most likely you do just have the clutch release slave cylinder that releases the clutch when you apply the petal. You need to bleed the slave cylinder of any excess fluid or air that may have entered the line if you opened it at any point. You need to bleed it as you would a break cylinder and this should fix ya.
good luck.
good luck