Extremely low gas mileage but no obvious cause

[ciper]

I'm a long time lurker and this is the first question I couldn't answer from searches. The car in question is getting terrible gas mileage in both the city and highway and I cannot find the cause. I have checked or replaced the most common items including -

Air and fuel filter
Plug and wires
Both oxygen sensors
Properly inflated tires
Correctly adjusted throttle kickdown
Fuel injector cleaner
Fresh tank of 89 octane gas after computer reset


The car drives fine especially after new tires/wheels/struts/springs and motor mounts. There is no carbon buildup on the bumper. No check engine light and it passes smog. There was a small exhaust leak near the muffler but I have repaired that. My last thought was that the gas must be leaking out somewhere and causing the mileage to be bad but I inspected the car multiple times and there is no fuel smell. I must be missing something obvious. The ONLY part I can think of that might effect this would be the thermostat but the car comes to normal operating temperature in a short amount of time and doesnt overheat.

Do you have any suggestions or ideas? Feel free to be technical as I have plenty of experience. The car is my nephews and I need your help otherwise we will sell the car for something that doesnt drain his wallet!

[ciper]

If anyone is interested please read this - http://www.acura-legend.com/vbulleti...d.php?t=106871