More likely a valve is sticking in the valve body due to varnish buildup. First check the rubber hose on the back of the vacuum modulator valve for signs a mouse chewed through it or there is transmission fluid leaking through it. A vacuum leak will make it look to that valve like you're accelerating hard and it will require a much higher road speed to up-shift.
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Friday, March 15th, 2013 AT 11:50 PM