Greetings from Georgetown, Texas!
What I've done to mine as an example:
With the Texas heat... and the Houston humidity, reduce watering to every third day and only water the dirt, not the leaves; move them to an area with a bit more partial shade, but still catching alot of radial heat; you may try adding about 1 or 2 teaspoons of Epson Salt to a gallon of water and pour it on the soil...not the leaves, about once every two weeks until you begin getting rid of the yellowing.
I am not suggesting this can/would work for yours, as every pepper plant has a mind of its own about how it wants to be treated.
Check the Growing section of the forums, there is ALOT of great suggestions and methods talked about there that may give you ideas or ways to help out.