2005 neon issues

Ok, I will go far back and try to include everything, a few months ago, while
driving, it acted as if it had bad gas, sputtered and would not accelerate. I
shut off the car and restarted it and it worked fine, this happened on occasion
during the following months, but rare, and restarting it worked fine, the check
engine light did come on each time it happened, but did not blink or anything,
and would shut off after a couple days. Today when my wife was driving it, it
started to stay in second gear, no matter the speed or pressure on the gas. I
looked around on the web, and found that it was likely the input speed sensor
for the transmission. So I changed that. I took it for a test ride, and the engine
just raced on its own, then bogged down, raced, it was all over the place, and
the power brakes stopped working as well, made it very hard to stop as the
engine was trying to push the car, even when braking. Now when I start the
car, the engine just goes nuts, races real high and drops back down. I
switched back to the old sensor, but it still does the same thing. So I saw
somewhere to turn the key on off on off then on, and got the code p2074....
What can be wrong?