99 Cavalier 2.2 EVAP problem

I have a 99 Cavalier with the 2.2L engine. I’ve had a check engine light on for a while and it’s more of an annoyance than anything because when I read the codes I get a p0440 code. EVAP systems malfunction. I don’t notice anything out of the ordinary with the way the vehicle runs except every once in a while my cruise control kicks out with a slight hesitation. fuel economy is fine, I’ve replaced the fuel pressure regulator and checked vaccuum lines as best as I can. I’ve replaced the gas cap and had a friend check the purge solenoid valve with a diagnostic computer which is in working order.