The car has been having some odd issues, where driving along slowly in traffic in first or second gear at 3,000 RPM it sounds like there is an intermittent misfire, a slight rpm fluctuation and a slight lurch. I just swapped in new motor mounts and the car does not lurch nearly as bad, but the misfiring feeling remains.

I just pulled the sparkplugs and took a look.
The #1 towards the distributor is very dark and sooty looking, #2 is good looking and much brighter, #3 looks like #1 and is dark and sooty. #4 looks like #2 and is good. I swapped the plugs all around and will see if the color difference will change the clean plugs to dirty and dirty to clean.

what could cause this?