95 4runner overdrive problem

automatic, v-6, 4x4.
for some reason, the overdrive kicks in and out on the highway, with out a load. even in town, i find that the RPM's are higher than they should be. some times it works fine for about 3-5 minuts, than it messes up again. have you had this problem? what should i do?

It may be that either your engine is running cooler than it is supposed to or your computer thinks the engine is running cooler than it's supposed to. The first problem would be caused by a bad engine thermostat (sticking open). The second problem would be caused by a bad engine coolant temperature sensor. I would simply replace the thermostat and see if that solves the problem.