Rod Nock, but no broken rod or collar

So I have 2014 with about 168K miles on it. About 2mnths ago i was leaving work and suddenly the car was shaking. It sound and acted like i had a flat. So I looped back into the parking lot entrance got out checked the car. All seemed fine. I got back in started it back up and nothing seemed out of the ordinary. The noise and vibration that was just there was gone. There was no engine code thrown or check engine light. During the drive home it seemed and acted fine. Did so the rest of the evening.

Next morning when I went to leave however the engine started making a lot of noise and rocking. Now the check engine light comes on. When I checked it was a misfire in Cyclinder1. I knew i was due for sparkplugs. so just ordered them and coils and let it sit there tell I could change them. The problem continued after changing plugs and coils. So I took it to a shop as it was not out side my "I can do that myself comfort zone". So took it to a couple shops and they all said it was thrown rod or collar on Cylinder 3.

The quotes i got to fix it were 2x the value of the car. So looked into how hard it would be to do a JDM swap myself and saw it wasn't that hard. Everything is mostly bolt on with a couple parts to swap. So I went shopping and found what i thought was a decent one. After doing the swap, brought over fuel rail, egr, and intake. I went to fire it up for the first time. It started rocking right away. I did the normal triple check over every bolt, wire, and hose. It was all correct

I tore down the original block. I wanted to see the damage and what was actually broken. Possible even repair it/ The only damage I saw was 2 scars on Cylinder 3 pistons bearings, but the scars can't be felt when you rub your finger on them. You can only see the scratches. Everything else about it seemed to be fine. None of the pistons, crackshaft, or cam shafts seemed to have anything actually broken. There is no sign of anything that would explain the level of rocking i was seeing. I did discover the initial misfire was a failing head gasket. It had only just started fail by the looks. There was no milk shake any where yet, but I did see it starting to form.

The fact i have seen nothing actually broken combined with the other engine doing the same, I don't know if perhaps it's something else that could be causing the rocking. This time it seems like it is Cylinder 4 not 3, but i could be wrong.

Any one have some things to look for or check? I can drop pictures as needed.