Thank you everyone for your help!
I can relate especially to AngelaR's reply. That is my problem, to pay REALLY good attention to what I am doing & not go into "auto pilot"
The only thing so far that is working is to say to myself with the thread in the back "Knit 1, Knit 2, then change thread to the front & say Purl 1, Purl 2." & keep repeating that. When I stop I try to make sure that I always end with the thread in the front to start the next Purl stitch.
I want to master the rib stitch it looks so nice when done (right)