My shower will only get hot water 'sometimes'. Sometimes I can't get the hot water to even get luke warm. The sink works great and so does the other shower in the other bathroom. It says Moen on the handle. Is it a problem with the hot water heater or the shower? Any ideas would be great! Thanks.

If you have hot water to other fixtures, that eliminates the water heater as the problem. Sounds like you may need a new moen cartridge.