Aerostar overheats after cam sensor replaced

My 1997 Ford Aerostar cargo van with about 130,000 miles on the 3L V6 failed a function test on the smog test (though it produced only half of the allowed smog) and I ended up getting a new cam sensor installed.
That was the code which came up on the computer. After this sensor was replaced, the car's pollution output was the same but the Engine Check light worked at last. (The previous owner apparently removed the Engine Check light.)
The car suddenly began to have trouble starting on cold mornings. About the same time, I had run it close to empty several times so I added some fuel injector cleaner to the next tank of gasoline, thinking maybe it was just a little dirt from the bottom of the gas tank. It also warmed up a lot over the next week so I didn't have a reason to start the car up on a cold morning.
The next symptom: it began to overheat when idling during warm weather. The temperature guage went way up near red if the car sat at a red light while it was hot outside. It rapidly cooled when we got moving again.
I've asked mechanics to explain how replacing a bad cam sensor could cause these symptoms and there seems to be no answer. The Ford dealer's answer to everything is to buy a new car.
Any ideas on the overheating? I really want to know if this engine's headed for major trouble.
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snipped-for-privacy@gmail.com wrote:

My guess would be that they disconnected the fan and forgot to reconnect it. When the car is moving, the radiator sees airflow from the motion. When you're stationary, the heat just builds up.
Does the fan actually run?
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snipped-for-privacy@gmail.com wrote:

impeller corrosion". Seems to be a common problem on Tauruses. The fix is a new water pump.
I think your overheating problems are complete coincidence to the cam sensor replacement. The cold starting thing....hmmmm....???? Don't know. But, if the overheating problem is resolved I would give it a new fuel filter and plugs to start and see how it does. Work on the overheating first so you know it not something serious before you dump too much $ into it.
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ShoeSalesman wrote:

that is a good sign of possible impeller corrosion( so is alot of miles).
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