Honda Car Forum

I have a 1999 Honda Civic DX with only 103,000 miles on it. About a week ago I noticed a light rumbling noise coming from somewhere under the car. I was due for an oil change so I took it in. They said everything they checked seemed fine. The noise continued but not very noticeably and it was only when I first accelerated. Well tonight I was driving it on the hwy and I noticed the noise was getting louder and louder. When I got off the highway and had to brake and downshift the car shut off. I was able to restart it but I could tell it was hesitating to start. It then continued to shut off everytime I had to stop but I was able to get it home. By the time I got home the noise was a constant thing and it was really loud. It almost sounds like when you lose a muffler. My dad said there's a chance it's my catalytic converter and heat shield but would this cause the car to shut off?? I was also driving long distance tonight so the car was running at about 65mph for about an hour. I don't know what it could be and I just wanted to see if anyone has any advice for me. Thank you for any help I can get.