Help with 91 Accord?

My 91 Accord (near 200,000 miles) just recently started bucking. At neutral, idle and throughout the lower rpms it is very noticble. The bucking is still there, but HARDLY noticable at highway speeds. I've replaced the plugs and wires, but nothing. It is a hefty bucking too...shakes the whole car. There isn't a loss of power, as the car still gets up to speed pretty well. I've read up on some stuff about cleaning the egr...is this a possibility? The bucking used to happen once in a great while on startup, but it would go away as soon as I revved the engine a little. Now it seems to be here to stay. It seems like it is something simple since the power is there. Clogged catalytic...something in the vacuum system? Help! Thanks in advance.

i had the same problem with mine. it was the fuel system. i started by pooring in some gas tank and fuel injection cleaner. that made it better but not all the way. in the end i had to drop the tank and clean it out there was a lot of rust in the tank. also changed fuel pump while tank was down. pretty sure thats the problem