2002 Dodge Durango Transmission downshifting while driving

My 2002 durango recently starting shifting all over the place while driving down the road.

It will shift from overdrive to 3rd, then sometimes down to 2nd. Then it will shift right back up again. And then start the process over.

And no i'm not driving up and down huge hills, something is wrong.

I change the filter and fluid about 6 months ago, and the level is fine, no leaks.

Would the torque converter do this, or is there something electrical or else going on?

The transmission oil smells normal, and goes into forward and reverse quickly.

Any help would be great, thanks.

collegenathan@hotmail. Com