ok, if the shifter is in D, and you are at 45mph, when you let off the gas, do you feel engine braking? (i.e. you let off the gas, & you can feel engine drag slow the car) if you put the shifter in 2 and get to 45mph, when you let off the gas you should feel engine braking slowing the car.... if it's in D and you let off the gas in the same situation, NORMALLY you wouldn't feel engine braking. if you DO, then i would say yes, perhaps it's the modulator or a TV cable. you may have a malfunctioning speed sensor somewhere too - stuck 2-3 shift valve in the valve body.... tough call. if when your shifter is in D and you get to 45mph and let off the gas you get no engine braking.... if it feels like it's "coasting", but when you give it gas, it still behaves as though it is in second gear, i would definitely check for a stuck modulator or jammed up TV cable or kickdown cable of some kind. occasionally, a throttle position sensor throwing a bad signal can cause non shifting problems, but usually those will cause no 1-2 shifting too..... not sure about your trans though, it could be different. hope you get it figured out.