I don't think the Mr. Coffee gets hot enough to brew properly. The water needs to be just over 200 degrees when it hits the coffee, and there are very few automatic brewers that can achieve this.
I assume that you're also not grinding the coffee the night before and setting the machine to start automatically; that would also take a toll.
As to the amount of coffee, you might start out at two rounded tablespoons of coffee for every six ounces of water, and go from there. If your coffee is really muddy and bitter, you might try grinding it a little coarser. You might want to add more coffee than that, but much less will guarantee you a weak cup.
Otherwise, you might try a Chemex, which is a manual pour-over brewer that uses really good filters for a very clean cup. And since you have control over the temperature of the water, you know that you're always brewing hot enough. It's the same with a French Press, and if you don't like the sediment you can get a fine-mesh nylon filter that takes care of a lot of the problem.
I use one full cup of ground coffee for 32 ounces of water in a vacuum brewer, and I like that. So, everyone's mileage varies.