I have a 2007 ford ranger, 4.0 v6, 5 speed o/d automatic, with 32k miles. Runs fine, starts fine, idles fine, accelerates fine, but when it is first started it makes a popping or banging noise almost like a backfire but not as loud. It does when first started in morning, and may or may not do it on subsequent starts. It is not terribly loud, but enough to make me wonder if something is wrong. The check engine light is not on and there is nothing unusual from the exhaust.
Check the exhaust system for a broken hanger, bent heat shield or misaligned system. Try to duplicate the noise by brake torquing the engine. If that is not it this should still be under the manufacturers 3-36 warrantee. I'd schedule an appointment to drop the truck off and leave it overnight. The dealer must be able to duplicate the noise to make a repair.