No heat in back.

What is your question?

Heat was working good then it started to only work good when I was pressing on the gas. It gradually cooled when I let up off the gas. Then heat started to blow out only cold air in the front only. The back vent were still hot. Had my heater core flushed and now only cold air coming out vents in back and heat comes out The front only when I am pushing the gas petal. I have replaced radiator and holes, water pump and thermost. Fluids on full and stay full. Also fans come on every so often like it wants to overheat but hasn't as of now.

What makes this problem better or worse?

Worse when I take my foot off gas

How long has your 2007 Ford Explorer had this problem?

A month or mo