How fast going up mountains in my 1987 Crown Vic? 302 ci engine

See Subject.
If I can only do 40 MPH going up a 7% grade with 500 lbs of passengers/load, do I need to get my car fixed, or just get a bigger engine?

Well, still got the old 87 LTD. Don't do mountains anymore at my age. Now the car seems to have plenty of power since the last tune up.

Can't keep the coolant in the block though. Seems to leak from most places:

top and bottom over flow tank
thermostat gasket
head gasket
freeze plugs


I don't add water anymore. just muck to make it stop leaking. surprised this old steam engine still runs.