Need help finding power issues.

Hello I'm new to the forums so bear with me. I have a 2004 toyota tacoma 3.4 liter v6 prerunner 2wd. The truck is well kept up. Oil changes every 3000 miles, new breaks, new tires and when I get any codes new sensors are put in right away. The issue I'm having now is a loss of power when climbing hills or pushing down gas pedal to get to higher speeds. My tranny has to up shift twice just to climb a hill and when pressing on gas it almost mAkes a bogging like sound. Merging on the highway can be scary at times Bc getting to 55 + miles per hour takes a abnormal amount of time. Almost feels like it's running to lean or a faulse reading is being given causing truck to run leaner. I have had no codes lol up. I have replaced the following with brand new parts in terms to try and fix the issue: new mass air flow sensor, new spark plugs, transmission serviced and checked( Very little wear), both O2 sensors changed new, both convertors checked( honeycomb like was clear with almost no carbon buildup), and I put on a k and N cold air intake to try and give it more power again. I have been to 6 mechanics already, two of which drove my car while hooked up to computer and said there was no bad readings even when car was accelerating. They did however feel the power loss but could not diagnose the issue. Please help as I am done burning holes in my wallet?!

 

Fuel filter or fuel pump on the verge of death?

 

my '13 was doing the same thing. Yesterday it lost all power on the freeway at driving speed after acceleration problems that were getting progressively worse at each stop and start. Yeah, merging was a little dicey. The cat had already failed and been replaced at 10k and now at 17k the dealer is telling me it's the fuel pump. They suspect it was a faulty pump all along although they ignored me when I suggested that the first time it was towed in. I am not a happy taco owner right now. These components are supposed to be life-of-the-vehicle parts.