i keep having this problem that makes me feel like i'm going to vomit (namely because i think i might need a new transmission). when i speed up after braking, it feels like it doesn't catch and then it jumps forward. i'd say it's the 1st to 2nd transition, but it's an automatic so i have no idea).
at the same time, but potentially unrelated, i've had horrible mileage for about the same time period. i tried the e-85 for a tank and it dropped my mileage from about 25 to about 12.
Is a 2000 Taurus a duel-fuel vehicle? If not you should never put e-85 in it, because the ethanol burns too quickly for the engine to take advantage of and ethanol, unlike gasoline, can cause galvanic corrosion of engine parts.
The only other thing I can think of is that you have a slipping clutch, but I don't know how clutches work in automatic transmissions.