Modifying your driving habits will eliminate the need for any device. Though I am no expert, I believe the situation is created by accelerating excessively. The internal computer derives the acceleration as a speedy one, in which case, wants you to shift into 4th (I believe this is for smog, catalytic converter or CAFE standards). I used to encounter the same problem, but rarely have the problem anymore, once I understood. However, if this is not a proper workaround, the CAG is your solution.
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Steven2001 Intimidator Coupe, 19K miles