CAN A TRANS SHOP RUN TEST ON A TCM OUT OF THE CAR TO MAKE SURE IT'S GOOD?

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I OWN A DODGE INTREPID 96 I TOOK OFF IN MY CAR THE OTHER DAY FOR THE FIRST SIX TO SEVEN MILES THE TRANSMISSION SHIFT FINE WHEN I CAME TO A STOP THE TRANSMISSION DID NOT SHIFT DOWN PROPERLY IT SHIFTED STRAIGHT IN TO FIRST AND STAYED IN FIRST NO MATTER WHAT I DONE I CAN LET THE CAR COOL DOWN AND IT DOES THE SAME THING EVERY TIME. I THINK IT MIGHT BE THE MODULATOR VALVE BUT I'M NOT SURE IF YOU HAVE ANY IDEA PLEASE LET ME KNOW..UPDATE-- changed TCM, doing same thing & still no chk engine light coming on.