gas mileage/f valve

[mrgolf77@xxxx]

Hi List,
I have been wondering if I should be concerned about the mileage my car 
has been getting. I filled it up 5 times now and set the trip odometer and 
every time. I got about exactly 185 miles until the low fuel light came on. 
Once the light goes off and I put gas in it holds 10.5 gallons. So 185/10.5 
is about 17.5MPG highway. I am not that hard on the car and drive highway 
most of the time. I never run the A/C and don't do any city driving. Mainly 
just to school and back which is straight shot 2 lane highway. The exhaust 
doesn't smell strong but I guess it still could be. The frequency valve is 
buzzing away but maybe not correctly. I would rather not take it to a shop 
if I can help it. Is there a way to test the 02 sensor pulse? The whole 
fuel system is new and I have not touched the air/mixture screw...yet.
also, when I hit the full throttle micro switch shouldn't I hear a change 
with the frequency valve and a slight raise in RPMS? That is not happening. 
The car starts with barely turning the key even in the cold so I think the 
cold start valve is fine.

Thanks
David