Hi,
We have a 2-handle kitchen faucet that has lost pressure. The sprayer works great though. Water pressure is normal everywhere else in the house so I know it's just this faucet. I've checked the aerator and it's clean... also, we've noticed a high pitched noise sometimes with the hot water (both temps work at this time). Based on research, we were thinking the diverter? But how would we find out?
Thanks!

Sounds like you have some debris in the faucet that is restricting the water flow. Try removing the valves (or cartridges) rinse them out and reinstall them.

Actually the diverter closes the flow to the spout when the spray is used, so I would not suspect the diverter. If both hot and cold flow from the spout is reduced with the aerator removed, I suggest removing the spout and run a small wire through it to remove any possible debris. If hot only is reduced, turn off hot stop valve, remove stem to hot valve, place a cup over it and open the stop valve briefly to flush hot valve.

The way I see it, water is getting through the cartridges just fine, other wise you wouldn't get good pressure at the sprayer. Also, if you have removed the aerator, and still no good flow from spout, I agree, hd, that you have a diverter issue. Sounds like the diverter may be stuck mostly in the spray position. Try pushing the spray nob quickly on and off over and over again with the water on to try dislodging the diverter. This has worked for me several times, but certainly not always. Other than that, you will most likely need to remove the diverter, and clean or replace it. How you will do this all depends on the brand and style fuacet you have. Either way, the diverter should be located under the spout in the fuacet body.