So I have a very odd problem with my 2006 Pontiac Grand Prix. The car drives and runs great, however I have come across an issue that stumps most people and mechanics I have asked. I am able to turn the key in the ignition and the car starts up fine, it runs great and drives perfectly fine, but when I park the car, turn the key off and remove it from the ignition.. the engine keeps running as if I never turned the car off to begin with. The car will run for approximately 5-15 seconds after taking out the key. After the car does this, the next time it is started, it starts up for 1-3 seconds and quits.. but then starts up normally after that. Sometimes when I go to turn the car on, the fuel pump fails to kick on and the car won't start at all, only crank. I have had the car scanned multiple times and what usually comes back amongst a list of various things is the Body Control Module. This makes sense due to the fact that my air conditioner kicks on and off while the car is off, and a couple of interior lights stay on while the car is off (yes, this sometimes drains my battery completely). I understand that a body control module can cause interior lights and air conditioner to run while the car is off, but could that be causing my engine to keep running after the key has been taken out?