Mountain Dew usually has less caffeine than a cup of coffee does depending on the amount of Mountain Dew you're drinking.
A 12 oz can of Mountain Dew contains around 55 MG of caffeine while a 16 oz cup of coffee contains as much as 320 mg of caffeine.
So Coffee will usually have much more caffeine content than Mountain Dew or any other caffeinated sodas.
Still coffee is much better for your health and kidneys than Mountain Dew or other sodas.