2000 Audi A4 can not start when hot smells like flooding

If I am reading the post correctly you're having a problem starting only when the engine is warm/hot.

A couple of common problems with these cars is air leaks and engine coolant temp sensors. The smell of flooding (or raw fuel I assume) would be more likely related to a faulty coolant temp sensor. They short out internally and set the fuel mixture (rich) for a freezing temperature. Was that the "sensor" you replaced?

Crank Position Sensors are also known to fail when hot and give similiar symptoms, but not as common on VW/Audi.
Have you checked the control modules for any codes? Even if the MIL isn't on, there could be some useful data stored in the ECU.