Is there any type of hierarchy of possible causes for problems like this? What's the most common problem, second most common, etc?

I know a friend has stalling problems with her 1990 420SEL and there were a number of possible causes. We still have not covered them all, and it's still stalling on acceleration unless the car is fully up to temp.

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OBK #55

1998 Lincoln Continental - Sold
Max 1984 300TD 285,000 miles - Sold
The Dee8gonator 1987 560SEC 196,000 miles - Sold
Orgasmatron - 2006 CLS500 90,000 miles
2002 C320 Wagon 122,000 miles
2016 AMG GTS 12,000 miles