1997 Hyundai Accent P0302 Misfire: Diagnosis and Fix with Cylinder 2 Exhaust Valve Warping

I recently purchased a 1997 Hyundai Accent SOHC 1.5 with 115,000 miles on the odometer. After connecting my OBDII scanner, I received fault code P0302, indicating a misfire in cylinder #2. I followed standard troubleshooting steps: replaced spark plugs and ignition wires, and even swapped out the #2 fuel injector—yet the misfire persists. The code clears after driving but returns within minutes. I tested all spark coils and confirmed they are functioning properly. I also switched spark plugs between cylinders to rule out plug-related issues, with no change in the P0302 reading. The engine runs roughly at idle, but the problem disappears at higher speeds—up to 4,000 RPM. I performed a compression test: cylinders 1, 3, and 4 show consistent readings of 180–200 psi. However, cylinder #2 only registers about 28 psi—a significant drop. I inspected the pistons by removing the valve cover and manually moving the cam; all valves appear to move freely. I have now ordered new piston rings and bearings for cylinder #2, as I suspect a compression issue. While visually inspecting the rings, they look identical across all cylinders—no visible wear or damage. However, without precise ring gauge measurements, I cannot confirm if there's an underlying issue. I'm also planning to rework the engine head. My question: could this be due to a warped exhaust valve? The misfire is likely caused by poor sealing in cylinder #2. I’ve just confirmed during cleaning that the number 2 exhaust valve is slightly warped and not seating properly—this explains the low compression. What could cause an exhaust valve to warp over time, especially with only minor deformation? How critical is this issue for engine performance and longevity? Thanks, Troy