Welcome to the forums!
My father once owned an 88' Park Avenue as well. The biggest problems he had with it were problematic window regulators (particulary the driver's door, the window glass literally fell right inside the door)
If you have the automatic trunk lid pull-down feature, by all means do not slam the trunk shut! I learned this the hard way
The shocks and struts were all badly worn (originals with over 130k on them!)
The engine and tranny both performed flawlessly, smoother than my 92' PA!
You're lucky to find one with so few miles on the odo!