Mine used to do that, and it was always when it was under load climbing a hill. Then one day it quite completely (on a hill of course). A mechanic found the coil was shorted out. New coil and the problem was fixed for good.

90 Montero, 2dr, AT, V6, LSD, AC, KYB shocks, bouncy seat, 182K miles, JDM engine, 87 Starion seats, tow hitch
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