If you have a 99 and are boosted, check the fuel vent valve which is located under the car right in front of the gas tank (towards the front of the car) The valve is not designed to see boost and the inner thin rubber diaphragm will eventually tear and cause that code. This is what it looks like:



If its not that, check the EVAP canister behind the front bumper passenger side vent. This can also be adversely effected by repeated boost.

If it is one or both of these, you can solve the problem(s) long term by using a 1 way check valve.

Good luck!

1999 Eclipse GS
Built motor
Hahn 16G Turbo w/ FMIC
Hahn Stage 5 Portfueler (270's & 500's)
Zeitronix Zt-2 wideband w/ 3.5bar MAP
3" SS Turbo Back
CM Stage 4 Clutch and Fidanza Flywheel
Baer Big Brake Kit