1998 Mazda 626 engine flooding

Car runs great after it gets started. To get it started is a major ordeal. I have to hold the key on and crank the engine none stop for at least 15 to 30 seconds before it starts. I get a strong odor of gas. I've checked the plugs during this and found them to be wet with gas. I'm sure it's flooding out but why. I've replaced the engine coolant temp sensor, new plugs, wires, coil and crankshaft position sensor. Any help I can get on this matter will be greatly appreciated. Thanks.