Second try...
I just installed the Post Image Max Size feature as a replacement for the failed Limit Image Width feature. This one seems to be working better.
The Post Image Max Size feature will limit the size of embedded images. Hopefully, this will prevent larger images from blowing out the column width and forcing scroll bars on the page.
There is nothing you need to do to use this new feature. Image resizing is done automatically. Clicking the reduced thumbnail will display the full sized original.
Example:
This 800x600 was automatically resized to 550x413.