Howdy. I have a 2001 4Runner with Auto tranny. I have an issue under acceleration. Between 2300 and 2600 rpm in 2, 3, and fourth gears, I experience a fluctuating engine rpm that seems to clear itself if I get out of the gas and get back in it. I'm never at full throttle, unless I'm on the racetrack in my racecar, I see no need. The surging/hunting happens in spite of constant pedal pressure. I don't know much about auto trannys, but is there some kind of solenoid that engages/disengages the torque-converter from fluid drive to full contact that could be failing? I took it to the Toyota dealer and he changes plugs/wires, fuel filter. He thought it might be bad gas, but it's still happening three tanks later. Any suggestions what it might be? I brought it home and cleaned the air flow sensor and the k&N filter and changed the ATF fluid, but still no change.

Help? Is anyone out there?

by fluctuating engine you mean? like the rpm's suddenly jump with no acceleration, or the engine stumbles? Hard to diagnose over the internet sometimes

under constant pedal pressure, the engine rpms run up, then around 2300-2400, they drop a few hundred rpm, then up a little higher, then a drop then up a little higher still, then a drop. Once it reaches 2700 or so, then the acceleration commences normally.

TPS, or crank sensor?

Is there a way to test those sensors?