Mercury Keeps Stalling in Traffic

I have a 1988 Mercury Grand Marquis that keeps stalling in traffic. It sometimes can take up to 5 minutes to be re-cranked, although typically it's just a minute or so. It SOMETIMES is proceeded with hesitation and choking
off, but not always--sometimes, it just suddenly conks out.
Previously, what would happen--but it doesn't happen anymore--is you'd crank it in the parking lot & keep having to re-crank it sometimes 4-5 times in a row, with it stubborn to stay cranked. Once you were able to take off with it, no more problems--and none on the road at all.
Some have suggested it could be the fuel filter, the fuel pump, or control module. One even suggested vapor lock, but another said this is impossible with a fuel-injected car.
What is the most likely scenario for something like this?
LRH
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Larry R Harrison Jr wrote:

    The first thing I would look for is fuel starvation. You do not mention how many miles or what had been done.
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IAC valve or ignition switch. Clean/replace valve, replace switch (it's a fire hazard anyway).
Larry R Harrison Jr wrote:

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If these cars have known ignition switch problems, I would surely investigate that.
However, I once had a intermittent crankshaft position sensor that made for real hard starting, then ran ok once it got warm. Similar to the problem you used to have. You can test it by checking for AC voltage on the connector while cranking. Thing is, you have to check it a time when the car won't start.
-jk

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