2002, SR5, 4WD, 170,000 miles

While driving, or starting from a stop, my 4Runner will lose power. It’s as if I took my foot off the accelerator. The engine doesn't die, it's just that the RPMs drop to idle and there is no response to the accelerator pedal. It doesn’t matter if move the pedal, floor it or do anything else. The power just cuts out. Within 1 to 3 seconds, it will regain power. However – and I think this is interesting – the power doesn’t come back with the power equivalent to the pedal position. It always ramps up slowly as if I’m starting slowly from a stop. In other words, if I have the pedal floored, when the power returns, it doesn’t jump to full throttle. It slowly builds back up to whatever position I have the pedal in.

The problem comes and goes. It will last for a few days, then be gone for weeks.

If it was the throttle position sensor, would the throttle slowly build up like it does or would it suddenly return to whatever position the pedal is in? Could it be the ECM?

I originally had a long crank issue that turned out to be a vacuum leak, but in the process, I did A LOT of work. All of this has been done

- Checked and cleaned all grounds in the engine compartment
- Replaced plugs
- Replaced plug wires
- Replaced battery
- Replaced fuel filter
- Replaced air filter
- Replaced PCV valve
- Replaced fuel pump and pump screen
- Replaced front (AF) and rear O2 sensors
- Replaced Fuel Pressure Regulator
- Refurbished original OEM fuel injectors
- Cleaned MAF sensor
- Cleaned throttle body
- Disconnected battery to clear memory
- Smoke tested for vacuum leaks – replaced hose clamps and vacuum plugs
- Ohm tested Throttle Control Motor, Throttle Position Sensor and Accelerator Pedal Position Sensor – all 3 passed (the 2002 doesn’t have an Idle Air Control Valve)
- No check engine light and no stored codes
- Ran through 2 cans of seafoam
- Replaced every fuse related to the ECU or fuel injection
- Took it to mechanic twice and he couldn't find anything