Hey all. I have a 99 impreza outback with 260k; just breaking her in . I was on the interstate the other day and i noticed i was slowing down a little, so I gave it more gas and it seemed to bog down and lose power i really had to stomp the gas to get her to go, even when it down shifted i could feel the lack of power. But when I let off the gas a bit i felt the acceleration come back noticeably. This went on till I got home form time to time. It didn't do it for a couple days then did it again on the hiway, and when I was coming back through town. It seems to happen when it warms up or has been running for a while. There is also a hesitation of downshifting now if not coming to a complete stop or giving it gas to pass someone.
I checked the fuel pressure pre-regulator and it was 35, would raise to 40ish when given gas but would drop back to 35 even with throttle open. I replaced the MAF sensor, but it was a cheap one and my car ran horrible with it so I'm guessing mine is ok, unless someone thinks I should buy another one and try it. I have new plugs, wires, fuelfilter (although I think it may be flowing backwards), checked for vacuum leaks (broke the port on the purge solenoid that runs to the intake manifold), and checked to make sure the knock sensor wasn't cracked or anything.
Any help with this would be very helpful as I have a 1700 mile trip coming up in three weeks!