Low water pressure on kitchen sink

The last few days the water pressure in my sink has sucked. Our house is about 7 years old so thats how old the faucet is. First thing I did was take the sprayer off and the water coming out of the exposed hose was low so I know its not the sprayer. Then, I turned off the cold water valve and took connection off. The water seemed to come out pretty strong from the tube. Which makes me thing it has to be an issue with the faucet line somehow. I took the entire hose off and ran some water through it and tried to blow through it to see if anything was stuck. There seems to be some build up at each connection which I cleaned out.. After all of that, still sucky water pressure. When I first turn it on, I get great pressure, but within seconds it weakens. Any other thoughts before I call a professional and pay through the nose?