I have a 2005 dodge neon and I was driving down the road and it just shut off. Could it be the timing belt?

Driving down the road and my dodge shut off, it will turn over but does not start.  My husband changed the cam shaft sensor and it still does not crank. He also changed two of the four spark plugs.  Everything still works like my windows.  My husband said he smelled gas coming from the engine when you try to crank it.  He thinks it is the timing belt. We tested where the spark plugs are and 1 and 4 do not have any pressure readings, and 2 and 3 have pressure readings.  I need help and don't have a lot of money to keep spending money to figure out the problem.