Everyone is giving you good advice, but you really need to buy an inexpensive code reader. You can get them on Ebay for $30. If you had a code reader I would tell you to put the old coils on, but switch their positions to see if the misfire follows the coil. Our focus on cracks in the coil/wire/plug is because you mentioned it was worse when damp. It could be an injector, but that would not change with differences in relative humidity.
Don't assume the JY coils you bought are good.
Why do you think it is still #3 that is misfiring? Without a scanner it is difficult (but not impossible) to tell.
2001 Bonneville SSEi (retired at 365,000 Kms.)
2014 Jeep Grand Cherokee Overland (yes, I know its not a GM)