1990 Honda Accord Car shakes, doesn't accelerate correctly.

Hi,

My car was running fine until one day all of a sudden I felt some random shaking. It's a real loud chug chug sound. Lately its been getting worse. I tried to drive up a hill the other day and it had no power at all. I drove it on the freeway and got it to sixty but it wouldn't go past that. One time I swear I felt it go back to normal for just a second and I felt a burst of power but then soon enough, I had trouble accelerating. My friend said that it might be an exhaust problem or something blocking my exhaust system. Everytime I turn it on I hear a loud chug chug sound, kinda like a lawn mower. It's really loud! You can hear it from inside my house. Also, when I'm driving it I get a really bad wiff of exhaust or burning smell coming through the inside of my car.