My 1990 Honda Civic is losing compression and will not accelerate up hills. I can hear a hissing noise coming from what seems like under the car? I am not much of a car wizard, but I am wondering what this could be. It has 142,000 miles and I would hate to have to get rid of it.. When it is not climing a hill, it runs fine? I have also been hearing a rattling noise that has been getting progressively louder, that is coming from somewhere inside the exhaust. This has been going on for a couple of months, but didn't seem to hinder performance. Any thoughts?

Thanks for your help.

PBRTN

 

Catalitic convertor maybe.