So I'm pretty sure I have a bad sensor. Car runs great most days, but whe the temp drops down into the 40's she starts idling rough. During freezing temps, it has been so bad it threw the "misfire detected" code. In fact, once during freezing temps I had to keepitabove 2k RPMsor it would die. I held it there for 20 seconds or soturned it off and restarted it, and she idled (not perfectly, but it didn't die). The rough idle gets better as the engine warms up, but never goes away entirely. Otherwise, there are no codes, so I get no help from the computer. She has no hesitation whatsoever and idles perfectly in warm weather.

I figure the IAT sensoris my likely suspect, but the IAC and ESC modulesare possible as well, as are the TPS and MAF. Anyone know quick tests (or even better, the typical voltage/resistance values) for these sensors? My IAT measured 2.8 Kohms on a cold day(45 degrees or so). This doesn't seem unreasonable, butI'm waiting on a warmer day to test it again. My clever test is to replace the IAT sensor with a resistor that matches it's warm-day resistance and see how she runs on a cold day, but that will take awhile. I have no idea how to test the IAC, and I have no idea what the idle and WOT voltage of the TPS should be.

As for the ESCs, I've heardthey output a fixed voltage normally, and I've also heard they only output voltage when a knock is detected (being piezo-electric, this makes more sense). Obvoiusly, I need to know which case is correct to troublshoot them, and if the steady voltage is correct, what should the voltage be?

I know it's a ton of questions, but any help is appreciated. And I don't mind throwing codes during diagnostics, I have a scan-tool. I will point out that I bought this car used, so it could be a custom fuel/timing map giving me this grief.