Evap leak hard to find

[10GoodAveo]

I have a 2010 Chevy Aveo with currently around 76,000 miles. All of a sudden a month ago I had my check engine light come on. The code I received was P0496 with erratic idle and crazy rpm movement while trying to slow down the vehicle feeling like it's still moving when coming to a complete stop. The code says "EVAPORATIVE EMISSION SYSTEM HIGH PURGE FLOW" I have done research and code say's common fix is to replace the purge valve solenoid. It didn't fix it because the code keeps coming back after i clear it and once in a while the car's idle is erratic with idle rpm jumping while trying to slow down. I have replaced 3 purge solenoids because they were found to be stuck open with the connector off and evap vacuum hose that runs to back of evap canister disconnected. It keeps sucking in air while i put my finger on the right side pintle. I checked the evap canister and replaced the vent valve control but nothing fixed this issue. I heard you must be getting bad parts or the pcm keeps shorting out the sensor having it stuck open. Other people say, rare fixes are replace fuel cap or fuel filler neck. I don't want to put anymore parts in this vehicle until I am sure what's going on and why it every purge valve i get keeps going bad. If you ever had this problem what did you do that fixed it? It has to be closed not sucking any air in when the sensor is disconnected or the codes with erratic idle will keep coming back intermittently. The strange part about this condition is, sometimes there is no code and the cars idle is perfect, other times code comes back and car still runs perfect. You never know how it will act. If it's going to run rough or stall out. That's the crazy strange part about this problem. The computer keeps making the sensor go into open loop, not closed disconnected like it should be.