sounds like your transmission is shot.

The type of gas you use would not cause the problems you are experiencing.

Since the problem happened while you were driving, I doubt if the problem is
due to a linkage problem.

What is the recent maintenance history?  By any chance, did you have the
transmission power flushed recently or was the transmission fluid just
drained and refilled?

Unfortunately, it sounds like a trans overhaul is in order.

Interesting thing happened on my old Mercedes once upon a time. As Ray
pointed out, I had just done a flush on the fluid a couple days prior to the
problem. And just like you, I was driving down the road when the engine
started to race, the car slowed down and stopped moving even though the
engine ran fine. After calling the tow truck, I went back to the car and
checked the transmission oil dip stick. Funny thing, it had oil half way up
the stick, like it had an extra gallon of fluid. After dragging it back
home, I pulled the pan and checked the filter. It was clogged!! Apparently,
the flush had cut loose the crud but not all of it had been removed. So,
after driving for a couple of days, it stopped up the filter. So all of the
fluid was on one side of the filter and could not circulate through the
trany. After changing the filter, everything was fine!! I drove it about a
week and changed the filter again (I was paranoid). After that, I drove the
car for over a year with no more problems.

Larry
In the back yard, under the oak.

The 2001 I think still uses the dirty but otherwise decent Aisin A-
series. So a possible rebuild at that mileage may be in order. The new
2007 U-series junk can skip gears, those have to be replaced with new
ones -- can't rebuild, according to a Toyota Jan 2007 TSB.