pours out a thick white exhaust

The car pours out a thick white exhaust while seemingly running on only 3 of its 4 cylinders what can I do to fix this? It is a 1998 Ford Escort LX with a 2.0L SPI engine. It has a brand new catalytic converter, radiator, timing belt, serpentine belt, and a rebuilt head. All of the gaskets have been replaced with new ones. When looking at the cylinder heads the one on the far left next to the timing belt is perfectly clean while the other three are exceptionally dirty. When running if the gas pedal is pressed the volume of exhaust increases.