Hesitation/Skipping Sensation P030400 fault code

[stinger123]

I have a 2018 V6 AWD Stinger with only 27000km on it. Completely stock. The last few weeks, I have noticed a skipping/gentle thudding hesitation type sensation only when accelerating gently to moderately. It can happen at speeds from 30-120km once the pedal is pressed about 1/3 to 1/2 and held.
I had a check engine light come on during one of these episodes last week for about 3 seconds before going away on its own. I took the Stinger to the dealer who had it all weekend and said a P030400 code (cylinder 4 misfire) was found. They cleared the code, took it for a test drive and said they couldn't replicate what I am experiencing. They examined spark plugs and did some kind of test on the ignition coil wire. Their final advice was "all systems working properly, customer to monitor".
Since picking the car up two days ago, I continue to feel this skipping/intermittent hesitating type sensation during certain accelerations. I can replicate it quite easily. The car still has powertrain warranty for another 2 years.
Does anyone have any ideas what this could be?

 

[Avant]

I would have had them swap the plug if they were in there already. If they tested the coil, then that should be fine. Next up would be you got a bad batch of gas.

 

[stinger123]

So after receiving the car from the dealer, it continued to hesitate with certain types of acceleration. A check engine light came on and the car went into limp mode (max 30km/h) last week. I took it back and they now say that 3 spark plugs were cracked. They are being replaced under warranty because this is considered premature wear with only 27000km on the vehicle. Has anyone heard of issues like this with 3 plugs going at once, when they were apparently just checked a few days before and fine....? I am wondering if there is some underlying problem I need to worry about, not to mention how soon the other plugs will need to be replaced. As a reminder, this car is STOCK.

 

[RedCal]

Coil packs have come up before... cracked plugs? did the mechanic drop them?

 

[stinger123]

Update for anyone interested. They replaced 3 spark plugs, engine still hesitating and CEL turning on when accelerating. They replaced the other 3 plugs and now all is well finally. It was covered under warranty, but I was without my car for about 9 days and had to take it in 3 times to get this resolved.

 

[RogueIV]

Coil packs have come up before... cracked plugs? did the mechanic drop them?

They can become cracked from the socket used in they are side loaded too much.

Update for anyone interested. They replaced 3 spark plugs, engine still hesitating and CEL turning on when accelerating. They replaced the other 3 plugs and now all is well finally. It was covered under warranty, but I was without my car for about 9 days and had to take it in 3 times to get this resolved.

I'm concerned why they'd even consider only replacing half of the spark plugs. That's poor form from the mechanic.