Also, I have noticed that pressure switch close to the air tank keeps tripping. I Changed the pressure switch(or whatever is called), but still doing the same thing. I live out in the country and have well water and like I said, some times the water just stops and after a minute o two, it comes back. Some times it does that, but some times it works perfect. What can the problem be?

Also, after the pressure switch trips the water pressure comes back. THen, it looses pressure and that's how it is constantly.

Moved to Plumbing from Electrical

What do you mean "pressure switch trips"
The pump switch is a pressure activated relay. Water pressure causes it to make or break contact which turns the pump on and off.
You said you changed it. Did you make sure that the pipe to which it is attached is clear. Sounds like you have some curd, rust or dirt in the piping blocking the switch. Causing a delay in the switch.

hkstroud thanks for your answer! I don't know exactly what is called: if it's pressure switch or relay... all I know is that is closed to air tank and keeps tripping and when it does it, the water comes with more pressure.

Here is a picture of how it looks like: http://www.northerntool.com/images/product/images/16151_lg.jpg

Tomorrow I will do what you suggested me to do and see what it does OK. Thanks again for your answer!