It's alright if the
fuel filter doesn't seem to "fill up". If you have it on the suction side, there might be air trapped, but it shouldn't be a problem. If its on the pressure side, again, might be air trapped in it, but the
pump shouldn't "push" more than a couple of lbs of pressure to the bowl anyway.
has the filter element discolored? like its dirty?
I'd take a gander at replacing the ignition coil and condenser.