2004 Mitsubishi Eclipse Running too lean

A lean fuel condition can be caused by:

* Low fuel pressure due to a weak pump or leaky fuel pressure regulator. (use a fuel pressure gauge to check fuel pressure at idle)

* Dirty fuel injectors. (try cleaning the injectors)

* Vacuum leaks at the intake manifold, vacuum hose connections or throttle body. (Use a vacuum gauge to check for low intake vacuum)

* Leaky EGR valve. (Check operation of EGR valve)

* Leaky PCV Valve or hose. (Check valve and hose connections)

* Dirty or defective Mass Airflow Sensor (MAF). (Try cleaning the MAF sensor wires or filament with aerosol electronics cleaner. Do NOT use anything else to clean the sensor, and do not touch the sensor wires)

AS a follow up, my mechanic went through each of the items you recommended. he replaced Mass Air flow sensor, checked for proper fuel pressure, all vacuum pressures checked, etc.

Still the light comes on, not all the time, but occassionally. The trim goes up, then down, depending on how long the engine is run.

He was checking to see if there is apossibility th e problem lies in the computer being reprogrammed wrong, or possibly the chip being replaced.

Any other ideas where I should turn? He thinks I may have to go to a Mitsubishi Dealer and have their mechanic check everything. I was hoping to avoid that.

Try getting the computer reflashed and see what happens