I have a problem with overheating in my 95 lincoln mark viii

Recommend combustion leak test.

You might be on the verge of a blown head gasket... There's a test for it you can buy from your local autoparts store.

A 4.6L DOHC V8 like the one in this vehicle is highly unlikely to have a cylinder head gasket failure. Anything is possible, but it's highly doubtful. I was at a Lincoln dealership for a significant period of time when these cars were new, and we never saw a single failure on this engine in either the Continental or the Mark VIII -- not to mention the sister engines -- 4.6L SOHC. When does the overheating occur? Is this on the highway? Is it sitting at a stop? Have you checked cooling fan operation?