My 01 is300 did the exact same thing. On this board and clublexus someone posted a fix to remove the accelerator pedal position sensor from the throttle body and cut away part of the cover over the connector solder joints and re-solder them. He posted a detailed explanation and a pic which I subsequently have not been able to return to. As a last resort I tried this as I was already planning to buy a new sensor so if I messed it up it didn't really matter. Well I must say the fix worked perfectly and it only cost me a couple hours time! Whoever figured that re-solder thing out is pure genius! I consider myself a fairly smart guy and I never would have guessed that particular problem.
The only thing I disagree with, and I've seen it a couple times on this board, is how the APPS works. It's a point of technicality but I spent 25 years repairing electronic and computer systems so it bugs me. The APPS on the 01 is300 has two potentiometers but they are not inverse they are different value ranges of resistance. The point of which is not safety but to develop a reliable difference of potential. In regular electrical systems difference of potential (voltage) is measured to ground (earth to be exact). On vehicle and other "floating ground" electrical systems "ground" isn't measured to earth (therefore not truly ground but the negative potential hence the - ) it is simply the direction of electron flow and the potential can vary. The purpose of having two pots of differing values is to create a voltage "divider" in which the difference of potential remains fairly constant (close enough taking into account physics) through a range regardless of fluctuating potential either negative or positive applied to the system. Otherwise in this system, because vehicle voltage is not super reliable, slight changes in input voltage would be interpreted as changes in pedal position.
Just my two cents worth with a couple extra thrown in!
P.S. the sensor will test good with ohmmeter, you'll just have to try the fix to know if that is the problem.
Last edited by HeyTimborino; 03-07-2017 at 11:05 PM.
Reason: Added tip