2005 Chevy trail Blazer ,changed coolant temp sensor, and now #4 cylinder is misfiring

Thank you for your answer! The code was directly for the temp sensor, but its worth noting that the temp gage shows temp normal at about 200 deg. And the sensor is not located by anything that coolant could have leaked onto. this is the most expansive system (ECM) i have ever worked on. the coolant temp sensor controls everything from vac adv, full trim, fuel delivery,,all of those issues can cause a #4 cylinder issue, it was an easy fix ,to easy,lol, i can't see anything i could have gotten wet or have disturbed . if i cannot get a good answer i will just take it for diagnostic, it probably a coincidence that a coil when out at that very moment but want to make sure before i start replacing unnecessary parts!

Hi Eric, wondering if you had any rain prior to this happening? A very common problem is our hood seals will allow water to drop down onto the #4 cylinder. Look down with a mirror prior to taking plug out, dry it out. I use a long screwdriver with a paper towel or rag wedged in there. I used a long piece of weather stripping from depot, and ran it in front of the hood seal, problem solved. You're right, location on 05 of the sensor woudn't allow water up top, luckily it's not 06 and newer, Chevy moved sensor to passenger side way in the back, PIA to get to. If no rain, no water, yeah, swap coils from a different cylinder, see if the P0304 follows to the swapped cylinder. Could be coinkidink, never know.