Engine kept running normally with switch off and key removed

Looking for any recommendations or suggestions. I have had one instance about a month ago where the engine continued running normally after I had turned the key to the off position and removed the key. I actually didn't notice it was still running until I returned to the van, I had been away from the vehicle for about 20 minutes with the key in my pocket. I cycled the key on/off several times and was not able to get the engine to stop. I was roughly 75 miles from home so I quit trying to get it to stop and crossed my fingers that it would make it home, which it did and switched off properly when getting home. Searched high and low for any reasons to cause the issue with no luck. Just due to past experience with Chrysler products I did thoroughly clean the battery post and cables. I have had bad connections cause weird electrical issues with other vehicles. Anyway, no other instances for several weeks, then Monday of this week (labor day) had an instance of returning to the vehicle to find the dash lights and radio still on after the vehicle had been parked for roughly an hour. I assume I didn't notice when I got out that everything didn't shut completely down. Got in and tried to start, the engine turned over fine but took more than normal to start, took 3 or 4 attempts and then was very sluggish/chugging, would not smooth out. Still sitting in park, tried to give it a little gas and it died. Switched to off position, back to start and it worked fine, started up and ran fine. Any recommendations, suggestions or magic wands etc, would be appreciated.