Re: 2005 wk 3.7
Since temperature is involved, it could have to do with the crank position sensor.
Also, if you have a scanner, you could check the O2 sensor operation. On a cold engine, the O2 sensors are not used for fuel trimming. When warmed up a bit, the O2 sensors are used for fuel trimming. If a sensor is getting bad, it could downtrim the fuel without need. I would at least check the 1-1 and 2-1 O2 sensor voltages, they should change rapidly from 0.2-0.8V. If one, or both is/are slow in changing the voltage or fixed at one voltage, its probably time for new sensors.