Oldsmobile/Buick Repair: STALLING WHEN HOT, coolant temperature sensor, buick skylark

Question
I have a '90 Buick Skylark, 2.5 ltr/4-cyl. When the weather gets warm--over 80 degrees--and after driving for a while, the engine will stall ONLY AS I'M COMING TO A STOP.  As long as I'm moving, it runs, though it may start getting sluggish as I slow and speed back up, then stalls when I get below 5-10 mph.  THE ENGINE WILL STILL TURN OVER, but dies as soon as I put it into drive. After cooling off for 15-20 minutes, I'm on my way until it gets hot...usually only 5-10 miles later depending on traffic, then it stalls again.

I was told it was probably the Ignition Module...if that were so, would the hot engine turn over, but die when the transmission is engaged?  I also read it could be the Crank Position Sensor.  Previously, it only stalled after driving on the freeway for awhile, then slowing down to exit.  The car would chug and sputter, then die.  It would restart, but die unless it cooled down for awhile.  Torque converter problem?  Do I have 2 problems going on?

HELP!  Thanks...

Carri  

Answer
Hi Carri,
Difficult one to say from a distance.
A couple other things it could be.
If it tends to run a little hot, and the fuel pump is old, it could be causing a vaporlock type condition due to insufficient fuel flow, which keeps the fuel cool in the fuel rail.

Another possibility is the EGR valve sticking open.

A bad coolant temperature sensor could also do it.

I'm sorry to just add more mud to the muddy water, but those possibilities exist.

I would test the fuel pressure, and try to have the tester connected during the problem. I assume the fuel filter has been changed?

The EGR can, and should be cleaned. The idle air control valve should also be cleaned.

Read this on coolant temp sensor. It can be tested easily.  http://www.chevytalk.org/threads/showthreaded.php?Cat=0&Number=1366279


I don't think it is a torque converter.
Also doubt the crank position sensor, but possible.

The ignition module could do it, and can be tested.

I suggest you go to Autozone, and let them connect their scan tool, and read the codes. They will do it free.
Then go from there.

But don't just replace the parts that the scan tool names.
A oxygen sensor rich or lean reading, for example, doesn't mean the sensor is bad. it could be correct, and just telling you a symptom.

Van