My kitchen sink often has very low water pressure whenever I turn it on, but when I press the sprayer the faucet's water pressure becomes normal. Do you all have any clue on how I could fix this issue?
Replace the transfer for the hose spray. Can't tell you where it's located without knowing the make faucet you have. A picture of the faucet will help.
Here is the parts breakdown for your faucet. http://s7d1.scene7.com/is/content/Pfister/ex-026-01
The part you need is #951-039. When ordering I would also get a new clip, part #950-111. All these parts are under the sink.