'01 Dakota 4x4 downshifting?

My 2001 Dakota 4.7L 4x4 seems to 'want' to downshift at odd times. It's an automatic transmission. It almost feels like the brakes are being applied.
The 'braking' lasts less than a second. Seems to occur when I am coasting downhill and I'm moving around 40-45 mph. But there's no full downshift. The rpm's sometimes jump up a little, as would happen with an automatic downshift at low speeds. There's enough fluid in the tranny and it looks clean. I had a full service on the truck about 15k miles ago. I've got about 105K on it. Any ideas before I take it in to the shop?
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My 97 was acting odd like that when it had a bare, shorted wire in the shift stalk od lockout. I replaced it and problem disapeared. "Rene Lopez" <

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