Eurovan 2003 GLS misfires under load

[JupiterTheEurovan]

Hey all,

I went form multiple misfires and a rough idle. Changed my spark plugs, cleaned throttle body, MAF sensor, and used fuel injector cleaner. Misfires are gone and rough idle is gone. Now as I accelerate up a hill quickly it begins to misfire again (vibrate and the check engine light turns on). Always cylinder 4 misfire and cooling system malfunction (from before).

I usually pull over, turn off the car and turn it back on and the misfire is gone and so is the vibration. I am now driving really slow and I take hills/freeway ramps slowly (sorry cars behind me). I want to fix the issue so I can use my V6 power.

Do you think its as simple as changing just spark plug 4? Which I just changed 1 mo (500miles) ago. Or does it sound more like a plug wire issue or a bad coil pack? How should I troubleshoot this issue?

I also have a new temp sensor and coolant thermostat to put in (if only I can get the belly pan off... arg)!!!

Best
Adrienne and her van Jupiter

[MrPulldown]

A couple of things come to mind.

Swap coil packs. See if the misfire follows the old CP #4.

Pull spark plug #4 and at least one other. Does #4 look different than the others?

Take a screw driver and hold the tip to the injectors. Hold the other end to your ear. Listen for the ticks. Manually rev the engine. Does the ticks sound different on #4.
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2002 EVC

[Abscate]

You don’t have plug wires on a coil on plug car, in the same way as older cars.

The moving coil pack trick will help isolate it.

If you want a trouble free T4, replace coils every 100k miles
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.ssS!