All I can remember about the film is the beginning starts with a crash landing of a spaceship and a scantily clad woman comes out of it.
The other part I remember is at the end of the movie, a jeep with people in it have to go through a cave where there are cocoons hanging from the top of the cave and inside are fat slimy aliens that look like the 'Michelin Man'.
I also remember seeing it on TV in the 80s around the same time as "Clash of the Titans".

I think it's "invasion of the Body snatchers"

http://www.imdb.com/title/tt0077745/