[Brian R.]

How is your gas mileage? If it is pretty bad, maybe you have a drag on your vehicle which is causing the AT to work harder than it ought to. Do you drive on really hilly terain? Is your radiator filled? Check the radiator at the radiator cap when the engine is cold. It should be topped.

When is the last time you checked your ATF level? Maybe you are low on fluid. Have you changed it in the last 100k miles?

If everything seems to be good, pull one of the hoses to the tranny cooler, hook another hose to the radiator nipple with both hoses in a receiver and then idle your engine. See if there is a reasonable flow of fluid through the radiator. You should get around a quart in 5 seconds if my memory serves.

See if your radiator is plugged internally (watch the flow with the cap off cold) or has a lot of debris blocking air flow through it. Does your radiator fan work correctly?