Hey guys just acquired and 87 crown Vic Ltd sedan brings back childhood memories I spent many an hour riding in the backseat of my fathers when I was young. Now the question it has the 5.0efi motor and she cranks up fine, if I let it sit and idle it will sometimes die but crank right back up and she. Shifting into gear if you don’t give it just a tad bit of gas it stalls out. Any ideas as to what the cause could be

Congratulations, and Welcome.,
Possibly an IAC issue, and/or debris build up on the throttle body/plate..