just bought a 91 ext cab 4x4 3.0, when drivin from take off trans shifts really quick like in overdrive before 20 mph any suggestions on what the problem is thanks

 

is your ECT button on? shifting before 20mph doesnt really seem like its shifting too fast espeicaly for the 3.0.

Bleeding and refilling your fluid is always something to try first. your manual has the information on what fluid to use or im sure someone else will know what to put in.