Not getting impressive fuel economy with the Civic

[DUBPL8]

Hi guys,

I have been experiencing less-than-stellar fuel economy in my Civic VX as of late.

When I first bought it in Feb of 06, I used to get at least 38-40; now I'm lucky to get even 32mpg.

Here's what I've done so far since owning it:

Spark plugs
Spark plug wires
O2 Sensor
Timing belt and water pump
A/C and alternator belt
Fuel filter
Distributor cap and rotor
Proper tire pressure on all 4 tires
Oil pan gasket and valve cover gasket replacement
Adjusted valves
New EGR valve
Adjusted timing to proper setting
Cleaned IACV and FITV
New catalyctic converter

One thing I haven't done yet is fuel system cleaning.

What the hell gives? It barely lasts me 300 miles on a full tank.

Also, the car is bone stock, with the original D15Z1 intact.

Thanks.