Thanks for the info. This is a great forum! I'm learning lots about my car by reading past posts. Although mine is almost 20 years old, it only has about 175,000 miles, so I hope to keep it running for a long time. The rust on the doors and tailgate will probably get it before the engine dies.

I guess there's always been a slight vacuum when removing the fuel cap, but I first noticed this problem the day after a long 3 or 4 hour drive. The car was very difficult to start, then when I stopped for fuel the cap was REALLY hard to remove. It was never like this before.

I'm going to look for hoses coming off the top of the tank. I had the tank out of the car years ago, but I can't remember the layout of the hoses. I hope I find one that's clogged!!!

Peter