my shift is stuck in park

Most likely it is a problem with the shift interlock. Check to make sure that your brake lights are working because the interlock is energized by the brake light switch. That is where I would begin. here are some shops, if you need more help: https://repairpal.com/mercury-repair-in-alpena-michigan

I had same problem and i ended up breaking my shifter off...thus i changed the brake switch and it fixed it. The brake awitch is located at under or behind the brake peddal... Itlike a ten dollar part at your local parts store and you can do it yourself. If the problem persist then its yourignition modual or stearing collum. But by he sound of it its a brake switch.