Well, I think I know why I went from 18mpg to 14, but I don't know why I am at 18 from 25. I guess maybe I could use some rebuilt injectors, or a little fuel pump rebuild.

The cause of the 14mpg recently was the blown #4 fuse. I drove my brother on some errands, and every time I used my blinker the interior light flashed, and the gauges went dead, all kinds of gremlins occurred, but no noticeable change in driving or power. I noticed the car was really thirsty at the same time. I found the blown fuse which fixed the gremlin problem, and today I realized the overload protection on the transmission is also on fuse #4. So I guess I was having a free for all on fuel from the changeover valve. Thanks for the help Mike and oldsouth.