I'm usually pretty well "in tune" with how my vehicles are running. Over the last few weeks, my truck feels as if it's losing power. For the last couple of days, it has developed a bit of an erratic idle (a small stumble every few seconds). No real loss of boost, and no discernable change in smoke, but the truck just seems to be less responsive - especially at lower RPMs and lower throttle input. It's taking longer to build boost also. Today I noticed that it is running quieter than normal as well (not a bad thing, but I'd like to know why). I've been running the gray CPS from Ford for about 2 years. I did have a small leak in the up-pipes (waiting for my new shop to get finished, so I have a place to fix that), but today I can't hear that leak anymore.