I would check the coil pack, I was having an intermittent missfire that became worse until the cylinder was completely out. It turns out my coil pack had cracked and allowed moisture to get in. I would start cheap checking and replacing the plug wires and spark plugs. Reading the plugs after pulling them will give you some indication of whats going on. If you don’t have a code reader handy to find out which cylinder has the missfire you can user a laser temperature gauge to check the temperature of your exhaust manifold at each cylinder. The missfiring cylinder will read cooler.