low idle on the autolite 4100

My fe390 was running good the other day but I shot some gumout in the carb anyway. Later at idle it was running rough but when I drive it it purrs. If there was some dirt somewhere inside why wouldnt it run rough at a higher speed. I didnt touch the two idle mixture screws either. What could it be Iam puzzled. What should I check for first. The plugs and spark plugs our good didnt touch anything else around the engine. Larry

 

The idle jets are the smallest in the carb. If you upset some crud in the bowls the're the first ones to get plugged up.