LSF

This is similar to my problem. It starts rough & loud at idle. Then as I drive down the street, it's loud and rough when I step on gas, smooth when it idles. Seems to resist going over 2000 rpms until I get up to freeway speeds. Then, when I return home, it's often normal the whole drive. Even if the car had been parked for hours. Change spark plugs a few months ago. Changed air filter. It's done this before and seemed to go away on it's own.