On morning cold start in Park-- catches immediately with RPM about
1100-1200. Idle is a bit rough-- though accelerates smoothly up to
3000-4000 in Park. After a few minutes, RPM drops to around 800 or so, idle still a bit rough.
The problem though is driving off at any point in these first few minutes, car chugs/stumbles right before up-shift point. The colder the outside temperature, the worse it is. After driving for several more minutes though, car then operates normally until restating the next morning.
Also, after a cold start, if I let it idle until the thermostat opens and the fan cycles on, it drives off normally.
Any idea what the problem is?