I've been unable to figure out what's causing this: my '87 240 has developed a habit of dying at red lights. It's a manual trans. If I depress the clutch while it's coasting down to the light, maybe 1500-2000 rpm, it dies. It's as if it's trying to drop to idle but it overshoots, doesn't catch itself and dies. If I leave it in gear until the rpms are around 600-700 and then depress the clutch, it doesn't die. What's going on? When it does catch itself, it idles just fine. It makes no sense to me. Any ideas?

I have to agree with Tony H.

Clean the Throttle Body.

William R.
1984 240ti
1980 262c (b21f conversion)

Your Idle Air Valve may be sticking. You may need to clean the gunk out of it.

Brian
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86 240GL, 86 740GLE & others

This and the throttle body cleaning are needed, as well as possibly an adjustment to the throttle linkage. I just fixed an 88 with similar symptoms. After cleanign the throttle body it was not idling correctly. Found that if I pushed the throttle closed, it DID idle just fine. The linkage out of adjustment kept the throttle open a HAIR and just enough to lift it off the throttle position switch. So it was running as if you had your foot on the gas a tiny bit. The idle circuit had been closed down to compensate.
The link rod adjusts like a little turnbuckle, loosen the jam nuts and turn to get the length set right. Careful with your little plastic ball-and-socket joints at the ends of the rod. They can be brittle at 15 years old, don't force them.
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Rob Bareiss, New London CT ::: 86 244DL, 87 244DL, 88 744GLE, 91 244: 805K total

You guys were right on the money. I cleaned the throttle body and the idle air valve with carb cleaner and the problem is completely gone, car is running beautifully. Thanks for your help.

It's a long shot, but check your plug wires. I had a car do that and couldn't figure it out for a long time. Turned out to be the wires.

Have you ever cleaned the Throttle Body? That might help. Check/replace the 25amp fuse on the front fender as well. I had similar symptoms and I replaced that 25amp fuse holder and did the throttle body cleaning during the same car maintenance session. The stalling went away.
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'75 Jeep CJ5 345Hp ChevyPwr and two motorcycles: it wasn't Volvos safety , it was Longevity that sold me

I had the same problem with my 84 240 DL about 2 weeks ago. It would run fine but die when coming to a stop. My mechanic replaced the AMM and it took care of the problem, but before you do that clean the throtle body as suggested by others. It only costs about 85 cents for the gasket and $2.99 for the carb. cleaner. New AMM is over $300.00.

The AMM was fine. For future reference, they're often available at the boneyard. I had to put my other '87 240 last year, paid around $25 for it. I have two grey '87 wagons, VIN's are about 1100 apart. For oddball stuff, I can often start swapping components until I find the one that solves the problem. It's a crude approach, but it works.