2003 Pathfinder losing engine power

Car: 2003 Nissan Pathfinder SE 2WD, 108k miles, Auto

In the last month or so my car has had a problem starting normally. After turning the ignition and the engine starts I usually have to press the accelerator very briefly to keep the engine from stalling. I changed the fuel filter and it got a little better. Now it cold starts are ok and I have to press the accelerator (again, very briefly) sometimes to keep the engine going.

Today, while entering the highway and accelerating, the engine seemes to have partially lost power and I could go no faster than 60 mph. The RPMs dropped and stayed around 2000 and no weird sounds. Engine sounded normal, but pressing the accelerator did not make the engine go any faster. I pulled over and checked the engine. All fluids ok, no weird sounds. After this I started it back up and it seemed normal. Went on the highway, shifted smoothly and normally. I tried a "passing" acceleration and the same thing that happenned before happenned again. Engine power dropped and could not go much past 60 mph.

This sounds to me like a fuel supply problem - electrical or mecahnical.

Any ideas before I take my car in?

Thanks for any advice.