How a car with throttle body injection acts when the fuel pressure regulator goes bad?

I have an 86 Cadillac Deville thats acting like its getting too much gas, and barely runs. I know that a bad regulator on a higher pressure multiport system can do things like that, but I don’t know if a throttle body system is more likely to close and not get any gas, or get stuck open and get too much. Also, could a bad o2 sensor cause anything this extreme?

- Well there is some truth in the answeres i read the regulator very well may be bad and this will throw a o2 sensor out of since and set the light no codes are set for the regulator
Usually when a regulator goes bad you will have a extended crank time mostly noticable when the engine is warm not all the time though
if you un hook the vacumme line at the regulator and it is wet then your engine vacumme will draw gas instead of air this will set the o2 sensor code indicating it is running to rich more gas than air
Now anouther option is one or more injectors are stuck open or slightly open this will make it hard to start and run extremly rough and cause serious damage.
So check the regulator if no signs of gas in vacumme line pull some spark plugs and look for wet and smell of gas on plugs have a friend turn the engine over with the plugs out and watch the holes for signs of fuel