Acceleration problem - 2000 Corolla

The cause for the residue would be your motor running rich. If it was lean, it would burn up everything and have hotter than normal exhaust. By running rich, not all the fuel is burned and that is left behind in the tailpipe. When you blew air on the air flow sensor, the engine computer tried to adjust by injecting more fuel, but since you werent actaully blowing the air into the engine, it resulted in a mix too rich to run and it stalled. But since its all fuel injected, to change all this I would think somehow the computer would have to be reprogrammed. The only reason it should be having these problems is if you are at a high altitude. There are less air molecules and therefore the motor runs richer. Temperature and humidity have something to do with it too, but it shouldnt be a problem at all. A car with fuel injection and a computer should be able to automatically adjust. I would say check all the sensors that need to be checked that have to do with the intake and exhaust, and check the computer. Often the computer adjusts the mixture depending on the exhaust sensors downstream, to tell how thoroughly the fuel is being burned.

Check that computer! Check that all the sensors are returning normal readings. mass airflow, manifold absolute pressure, o2, manifold air temperature, and throttle position. Those are the senors related to a fuel injection system. I don't know if its possible to check all of them. the sensors should be operating in a closed loop, where the computer adjusts various things to automatically compensate for the changing sensor readings.