1996 Ford Taurus hesitation in acceleration

If it acclerates fine after 30 mph would suspect a throtle position sensor you can only test acuretley with a scope.

Thank you, because I thought that it was maybe the transmission going.

It still could be a transmision if engine rpms goes up but your car dosent go any faster

PLEASE HELP. Now that I have changed the transmission, tps, and mass air flow sensor, the car is still doing the same thing, with the exception now that rpms have leveled out, but the car will accelerate up to 35 mph, when the car gets to 35 the rpms are at 5000, it still will not shift from 2nd gear to third, could this be the catatylic converter or O2 sensor? I put it on the dx machine, dx machine states O2 sensor, auto parts store states that if this is gone bad that the car will not do what it is doing, meaning the ablility to not change gears, I am thinking that this would affect the shifting of gears because the car is not getting enough air am I correct?