Okay, I have a 2001 Hyundai Elantra, about 220,000 miles on it. I'm the second owner.

I begun driving the car in early January, and when it was wet on the roads (from the snow) my car would shift gears randomly. It would go from 2,000 rpm to 3,000 rpm, when I'm only going 70 mph on cruise. It wasn't a normal acceleration shifting, it was like a big jerk.
It did it when the roads were dry with sunshine as well, so I know weather didn't play a role in it.
My dad replaced the CO sensors. I don't know what those are. After he fixed it, it was working fine. A couple days later, same situation. It would shift gears and the only way to get it back to the normal 2,000 rpm was to turn it off for about 2-5 minutes and then restart.
I stopped driving the car cause I felt it was not reliable for my 45 minute commute. I drive on the freeway, usually no more than 70 cruise to college everyday.
It's been about 2.5 months now (my dad drives it now) and it hasn't "jerked" or shifted gears.

I read posts online that people have had a similar problem. They said that the speed sensors need fixed.

Basically, my questions are...

What do you think is a potential problem?
Do you think it's the speed sensors?
Is there a difference between CO and speed sensors?

Thanks ahead of time!! Hope someone can help me out!!!!!! :liebe011: