I had the same problem you are experiencing. I couldn't seem to correct it. I bought a couple of different 1/4" feet and I still tailed off at the end.
I sew on 2 different Brother machines - a sewing/embroidery combination and a Brother Runway Wally World edition.
A friend recommended I buy an open toed foot that was a snap-on. That started me getting better. I use the left needle stitch setting, then change the width a bit and run the material even with the inside of the right part of the open toe foot to get my 1/4". Then I had to learn to slow down and watch the edge of the material all the way through the foot. I'm not perfect, but I am a whole lot better.
Another thing that really helped me sew straighter was some paper piecing I did. In order to stay on the line, you had to watch it closely. Getting even a little bit off caused some resewing. After you sew the same thing 10 or 15 times, you began to pay more close attention to keeping the edge of the material next to the edge of the foot all the way through the seam.
This is the foot I bought. It is a generic, so doesn't have the fancy markings on it, but I quickly found I didn't need them anyway.
http://www.ebay.com/itm/Snap-on-Meta...item3f2f9b1159