I just fix the fuel pressure regulator on a 99 hyundai elantra and im still having an issue..?

A fuel regulator hardly ever goes bad. I wouldn't fool with it. instead, I would be looking at the fuel filter. you can pull the filter and shake it out in a glass bowl and look for contaminants such as sandy particles. if so replace it. I would replace it any way. if symptoms persist, check your fuel pump pressure and make sure its within limits. If you think your flooding the engine, change your air filter. when starting your car, do not depress the gas petal.