91 Olds Cutlass, won't idle right until warmed up

Got a Olds from my Dad to drive. Car has been pretty good, but this
winter notice that when it is cold, it will start o.k., but will stall
out when you put it in gear. Condition continues, till it warms up,
which can be 10 minutes.
Won't seem to warm up that fast, so replaced the thermostat, seem to
help some, but condition still their. Since then, replace the IAC,
found it fouled up and dirty. Getting to engine lights.
I have notice the idle speed is the same, even when cold. Growing up
in cold parts of the country, all cars will idle higher when it is
first started in the cold. What controls the idle when the car is
cold? Condition reminds me of the days the choke was not working
right.
Tom

http://www.w-body.com is an excellent website/operator online community for
any further questions.

Sounds like you might have a malfunctioning coolant temperature sensor.
Have you checked that out? The idle speed setting is derived from an EPROM
map which uses, as an input, the coolant temperature sensor's reading.

Also, the Intake Air Temperature sensor (located on your airbox) is another
place to consider perhaps. But the coolant temp sensor is a known problem
area on those cars, so I would definitely consider it first.

> Got a Olds from my Dad to drive. Car has been pretty good, but this
> winter notice that when it is cold, it will start o.k., but will stall
> out when you put it in gear. Condition continues, till it warms up,
> which can be 10 minutes.
> Won't seem to warm up that fast, so replaced the thermostat, seem to
> help some, but condition still their. Since then, replace the IAC,
> found it fouled up and dirty. Getting to engine lights.
> I have notice the idle speed is the same, even when cold. Growing up
> in cold parts of the country, all cars will idle higher when it is
> first started in the cold. What controls the idle when the car is
> cold? Condition reminds me of the days the choke was not working
> right.
> Tom
>

I am wondering more about this temp sensor you mention. Come to think
about it, I have seen the fan turn ON a lot. I am wondering, if it
thinks the engine is warm and is turning the fan ON. Have you hear of
this related to the temp sensor. Could also explain why the vehicle
only really runs good when it is warmed up.

My story continues. Still haven't quite understood what is going on.
Today, it was much colder in Colorado and my son went to school. We
just replaced the themostat, thinking it was causing some of heat
problems. Anyway, the car was overheating when it was 10 degrees
outside. Sounds like a water pump issue. What does the group think?
I would think this could be causing:
- won't idle right when cold
- heater not putting good heat out into the car, even though the system
seems to be working
- overheating conditions
Interesting, this overheating condition does not persist, seems to go
up and down, however, my son has said it seems to be running hotter
than normal. The thermostat is rated at 195 and his guage is
indicating 220 to 230.
Tom

I figured out the problem. Turns out that the radiator fluid was just
low. My son told me he kept adding fluid. Small pin whole leak. The
fluid being so low must have causing the thermal sensor to get false
readings, and the heater not to heat. Possilble air bubble. Anyway, by
filling up and finding the leak, problem solved. Now I hope the stop
leak stuff works, or we get to replace the radiator.