Hey all......I own 2 '87 240's and I have the same problem with each. After starting and warming up for a minute when I put them in gear(automatic) to go, 9 out of 10 times they stall. I put in neutral or park and always they fire right up and go. Once they are up and running for the day it doesn't happen again until it sits for more than several hours. Always in the morning, sometimes after several hours........any ideas?.........thanks in advance

 

Mine does this to, but only if i try to hop right in turn it ona nd shift right away, if I wait 20 seconds. It's all good. Probably have a weak idle control valve.

 

What is the maintenanace history? I would clean the throttle body and look for vacuum leaks (split lines,etc). Make sure there are no holes in the large tube that runs from the air mass meter and the throttle body, usually the wires next to it will rub a hole in it - and allow in unmetered air.

You can also pull a spark plug to get an idea if its running rich or lean.

 

It can also be a coolant temp sensor that is starting to go out. I just replaced mine. I used a volt meter to measure the ohms on the bad one, a used one from the junkyard, and eventually a new one. The new one was getting about 4.3k ohm cold and it would drop to 600-800 ohms in boiling water (mine was from a water cooler with hot water). The junk yard one (which the car ran ok with but the check eng light would return) would get 2.3k ohm cold and 600-800 ohm in hot water. Finally the bad one gave me 4.3k ohm cold and drop to only 1.1k hot. Hope this helps...fyi if you do replace it save time and frustration by removing the intake manifold to get to the sensor.