98 Sunfire P440 Code

My 1998 Sunfire's check engine light comes on from time to time. Usually when it rains, but no always. It stays on for a few days to a week then off again, only to come back on a few days or sometimes hours later.
The code is P440 Evaporative - Does anyone know what this means and how to repair it?
Thanks for your help!

Check your gascap, and for damaged vent lines

I just took the car through inspection and the gas cap passed there - would that rule it out as the problem?

Could damaged vent lines also cause the car to buck and hesitate?

It hesitates when you first hit the gas, then as you drive it will buck, sometimes quiet hard. It feels at times that it is not taking up the gas (but has not stalled out). If you let go of the gas it immediately stops or if you floor it it will pick up the gas. This happens sporadically, sometimes worse on some days than others.

Also, do I need to take this to a shop to have them run tests on the vent and the vacuum lines - could this be the problem?

Thanks

I would 1st examine all hoses and vent lines, by squeezing them while engine running and see if same symptoms ( engine wants to stall or slow down )

Also, if you had a old garden hose, you can cut off and chunk and hold one end to ear and near vacumm lines to hear if leaks.

Since you also mention gas issue, may not be related but have you had your fuel filter looked at ? Maybe clogged. But i also beleive there is a evop line near tank as well which maybe clogged.

I've had the gas filter, air filter, spark plugs and wires changed as well as the oil.

I will now have the vent lines checked next.

Also, how do check the evap line and can that cause the hesitation & bucking?
Thanks.