2000 Cadillac Seville STS P0300 and P0303 Misfire Diagnosis - OBD2 Code Help

Hi, I have a 2000 Cadillac Seville STS with 172,000 miles. The On-Board Diagnostic (OBD) system shows both P0300 (random misfire) and P0303 (misfire detected in cylinder #3). I've used a basic scan tool to confirm the issue is specifically tied to cylinder #3. I've already performed several troubleshooting steps: - Replaced two coil packs - Installed new spark plugs - Swapped the spark plug wire from another cylinder and tested with a different injector on cylinder #3 — the misfire consistently remains in cylinder #3 - Conducted a vacuum leak test using carburetor cleaner; no obvious leaks were found. Interestingly, after extensive driving or engine manipulation, the misfire occasionally diminishes or disappears for a short time but always returns. The check engine light (MIL) blinks intermittently at wide-open throttle (WOT) in second gear when RPMs reach the upper range. Here is the freeze frame data: - TP: 0% - RPM: 671 - LOAD VALUE: 1.9% - AIR FLOW: 7.06 - MAP: 51 kPa - COOLANT TEMP: 199°F - INLET AIR TEMPERATURE: 123°F - TIMING: 5.5° advanced - SHORT TERM FUEL TRIM 1: +0.7% - LONG TERM FUEL TRIM 1: +3.9% - SHORT TERM FUEL TRIM 2: +0.7% - LONG TERM FUEL TRIM 2: +6.2% - SHORT TERM FUEL TRIM 3: +72.6% - LONG TERM FUEL TRIM 3: -70.2% - LONG TERM FUEL TRIM 4: +35.9% - SPEED: 0 MPH - OPERATING MODE: CLOSED LOOP Could a faulty crankshaft position sensor be causing this misfire? The engine starts easily and does not stall under any conditions. As someone with experience in carbureted and points systems, I suspect a shorted spark plug wire — but there are no wires on this vehicle. The plug boots appear intact, and neither the old nor new plugs show signs of fouling. I also tested by unplugging the oxygen sensor located at the exhaust manifold (before the catalytic converter). There was no noticeable change in engine performance, and when codes were cleared, no new fault code appeared. Any insight or suggestions would be greatly appreciated. Best regards, Ernie