Cylinder 1 Misfire Still...

[Radejr]

I have an 08 Cobalt 2.2 Ecotec.

I started getting a check engine light. P0301 is the code. I replaced spark plugs with NGK plugs. Code came up again. Swapped Coils. Code Returned. I hit a deer in this process had to replace radiator. Ended up running over it. I got the code cleared and it returned. About 3 weeks later I finally move my injector to a new cylinder still same code.

What my next plan of attack? I didn't gap my plugs because I thought NGK was already done, so I plan to gap them tonight. What gapping do they need? If that doesn't fix it what's my next plan of attack to diagnose the issue? I don't think it's related to the deer accident. Seems to be getting worse though. I have no lack of power taking off, but idle is rough. I was also thinking Chevron through it to try and clean the valves?

What do you think I should look at?

 

[YelloEye]

Well since you've eliminated coils and injectors I would say double check the correct gap on your plugs. You can find this info on the last page of section 5 (Service and Appearance Care) in your owners manual. Should be something like 0.040 in, but double check that with your manual. If you don't have your owners manual, GM still back to 08 on their website so I'd suggest downloading and storing it somewhere.
https://www.chevrolet.com/owners/chevy-manuals.html

Once you've confirmed that the gap is correct it's time to start looking at other items like the valve seats, piston rings, and head gasket.