Thank you for contacting us.
It is true that the issue could be over-watering, under-watering, or inconsistent watering.  All can lead to yellowing leaves.
In pepper plants another common cause of yellowing leaves is insufficient nutrients.  Light, frequent feedings with a balanced fertilizer are recommended.

Thank you so very much for the response.  I agree I was probably overwatering them a bit.  They get fertilized every few weeks but I'll try to alter that as described above. 

Any ideas about the "dirt" in the veins of the leaf?  I say dirt because that's what it looks like but it's within the leaf and not "cleanable."  This is happening on all of the pepper plants regardless of leaf color.  This ailment is causing necrosis at new bud tips and stopping growth.  Best Regards, Shane

A nutrient deficiency could cause the symptoms you described.  If this is the case,  more frequent fertilization will result in healthy new growth.

Another cause of discoloration on leaves and damage to buds is thrips.  Given their tiny size, they often go unnoticed.  Their damage can show up as either darkness or silvery areas.  The best treatment on a food crop is simply to spray the plants with a fairly strong jet of water to knock the insects off, the same as is recommended for aphids.  This can be repeated as often as necessary. 

Given the possibility of a pathogen, we recommend at the end of the season you do not compost the plants, but rather dispose of all affected plants with landfill trash.