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My car's had the hot start stumbling problem more often recently so I decided to try something. In my case, the problem seems like a lean condition, based on the intake backfires and the lack of gasoline smell or smoke in the exhaust. I also noticed that if the temperature gauge went higher than usual, like up to the middle of the M, that the problem was likely to happen. So I bought a 5 kohm Audio Taper Potentiometer and spliced it in to the water temperature circuit as a rheostat (two wires connected, one left open). Mounted it by the hood release handle in the cabin so that I could tune it when needed. It's basically the part behind the volume knob on an amplifier. The linear taper potentiometer changed resistance too fast (I had my ohm-meter in the Radio Shack store). It can only be used to add resistance so will only add more fuel. When the engine is running normally, I can't turn the knob, increasing the resistance, at all without the RPM dropping as the injectors stay open longer. But today I had two "hot start" cases where turning it stopped the stumbling and smoothed the running. I still had to wait about 15 seconds before I could take off, but it seemed to clear up faster, probably because the water pump was pumping more water, cooling the WTS down to true engine temperature. Plus, at least it was running well, instead of jerking and popping. My current theory is that the WTS overheats due to residual heat from the exhaust manifold (the only engine part that doesn't really get cooled by the radiator coolant) indicating a hotter engine, needing less gas. This may be why Nissan moved the sensor to the other side of the head on the P79 head. It's just a guess. Maybe the injectors also get hot or maybe it's just hot injectors and adding fuel still helps. Who knows. It really seems to work though. It's worth a shot if anyone else wants to try it.