well i decided that the problem is something with the o2 sensor, possibly a bad wiring connection. i unplugged it completely and voila, the problem is gone and it runs way smoother. somehow there is no check engine light, but still need to check everything and figure out what is causing the problem so i get my gas mileage back to normal. i also have a pm6 chipped with turboedit to run the 450's when i put them in.