If you press the release, gently wiggle the connector while turning 1/4 turns back and forth. It should come off.
Here are the directions for replacement. The attached pics correlate with the directions.
2004 Pontiac GTO V8-5.7L VIN G
Vehicle Powertrain Management Emission Control Systems Evaporative Emissions System Canister Purge Control Valve Service and Repair Procedures
Evaporative Emission (EVAP) Canister Purge Valve Replacement
1. Disconnect the EVAP engine vacuum pipe from the EVAP canister purge pipe.
2. Disconnect the engine compartment EVAP pipe at the EVAP canister purge valve.
3. Disconnect the EVAP canister purge valve harness.
4. Remove the EVAP canister purge valve.
1. Install the EVAP canister purge valve to the bracket.
2. Connect the electrical connector to the EVAP canister purge valve.
3. Connect the engine compartment EVAP pipe at the EVAP canister purge valve.
4. Connect the engine vacuum pipe to the EVAP canister purge valve.
Let me know if it doesn't come off. Note there is a rubber o-ring in there that may have a bit of corrosion on it causing the problem.
Let me know.
Images (Click to enlarge)
Monday, April 27th, 2020 AT 11:00 AM