Engine idle and P0440

About 2 months ago I went out to my car to start it and it started and then died. It would not hold idle. After reving and driving around, it started to hold a low idle at about 600-700 rpm. After about 30 minutes it was back to an idle of about 900 rpm. The problem did not occur again till 2 days ago. Same basic thing. After driving to work it would hold a low idle. When I went to drive it at lunch time the idle was back to normal. Then yesterday I get a SES light. I pulled the code and it gave P0440. I checked the gas cap and it seemed secure but refastened it anyway. As of today, the SES light is still on and the idle is okay again. Are these realated? What should I do next?

The EVAP system is no longer functioning, it's designed to reduce fuel emissions into the atmosphere.
suspect -
Gas cap
carbon canister
purge valve (fuse) ***
rubber hoses

Evap codes will normally not cause a drivability issue so I say the two are not related.

On the Idling issue, I would clean the IAC valve and its bore. If that does not help, you may need to replace the IAC motor.

It has been a while since I've seen another Utahn on here! :bigthumb:

On my 2002 GP SE the SES light come on (steady). Autozone read the code for me (P0440). I had an aftermarket locking gas cap that has been on for 5 years. I replaced the cap with the OEM cap and erased the code with Actron code reader. The SES has not returned (2 months). I re-examined the locking gascap and found that the gasket has multiple small cracks. Also replaced the connector hose comimg from the PCV since it seemed to be somewhat deteriorated. The hose is molded into a 'U' shape so bought the OEM from GM rather that use standard hose.