2005 Dodge Caravan smeels like

Just purchased van 8 months or so ago. Test drove fine. Overnight the van smells like weed I first thought that the place that replaced the drive shaft mechanic test drove it and smoke a joint or something. 4 months later problem still exist. Smells inside and out. It smells so bad I joke about it to my workers and a week later I walked out of the movies to police officers standing next to the van. Said the van smells like fresh weed, even had the k9 bark at under the hood. They searched under the hood and inside and out. Found nothing. Police could not believe they found nothing said they never seen nothing like this before. Current problems and repairs with the van are. Van dash light flickers and some time cycles, blinker are sometimes opposite. Sometimes turning blinkers on make the driving lights go out. Or dash gauges just turn off. Never effects the van running. New lower head gasket, drive shafts new, rear shocks, struts and mounts, thermostat, battery, transmission filter, flushed radiator, Can anyone please help, is it safe for my family to be in the car. One more thing it appears the van lived on a gravel road based on the dust and tires and so many other things. Thanks for your time.