S-10 Transmission blues :(
 

I am a new guy to the forum! I have grown up on Chevy and am looking for some helpful advice.
I own a 2000 Chevy S-10 2.2L automatic with 127000 miles. I have had a number of problems with the transmission since i bought it used in 2005 with 48,000.

The first problem started at about 65,000 miles. When traveling at 55-65mph, the transmission will slip out of overdrive and rev very high and the check engine light comes on. The only way to reset the transmission is to stop, turn off the engine, and then it works fine. This usually happens about every 2 months or so.

The second problem occurred a few days ago when I was backing out of my driveway. I went to put my truck in reverse it wouldnt engage. It took about 5 minutes of turning on and off and shifting through the gears to engage reverse.

I am in college right now, so money is tight. I am looking at trying to fix this myself.

What do you think could be the problem?