ok, let's take a step back and get some details. Water pump, t-stat, cap, electric fan are all new. When you had the water pump off, what did the block look like inside? Was it clean shiny metal, or rusty? Is the fan clutch working? what codes (actual #) have you gotten? It has 2 o2 sensors. 1 at the y-pipe and 1 after the cat. how old is the air filter, plugs and wires? Have you done a compression check? a blown head gasket, or cracked head would show up with a compression test. If you have a OBD 2 scanner, you can graph the sensors and see if any are not within spec.