the time it will run rich is that split second from 100% throttle while the thorttle plate is coming back to shut..

that takes what an instant of a second? that is when the car will run rich.

it spits flames because the air flow metere counts this huge amount of air adds fuel while the thorttle plate is closing and because the throttle plate is closing it sees the air as like 18psi of boost it then retards the timing and the retarded timing along with the slight richness is what pops the flames.

As soon as the TPS reads the throttle as being closed there is no more fuel injected to the motor until the iacv turns on.

next.