I have a Moen bathtub faucet/shower head. It has the pull handle with the cartridge inside. Last year, I replaced the cartridge because it was leaking and was the original (installed in 1976). The leaking stopped, all seemd fine. I never use this shower, my sons do. They are off to college etc. So, yesterday I used it for the first time in years. I immediately noticed low pressure from the shower head, unlike in our (wife's too) bathroom right behind this bathroom. So, I experimented and found that it is NOT the showerhead because the pressure is low even when switched to the faucet. If the water isn't on for a while (like first thing in the morning when taking a shower) and the faucet is turned on, there is very good pressure for about 3-4 seconds then it reduces, 3-4 seconds later it reduces even further and remains like this. It's enough to shower but isn't what it should be, like mine. I'm assuming it's a cartridge problem but find it unusual since, as I said, I just replaced it last year. Any help would be appreciated.