2002 Chevrolet Avalanche 5.3L with P0300 Code: Cold Start Issues and Rough Running

My 2002 Chevrolet Avalanche with a 5.3L engine has recently started exhibiting intermittent starting problems, particularly in cold weather. The vehicle has accumulated 88,000 miles and all original components except fuel filters. Previously, it ran smoothly without any issues. The issue began when I parked the truck overnight in a garage. The next morning (ambient temperature around 34°F), the engine failed to start normally. Instead of starting on the first crank, the check engine light illuminated as soon as I turned the key — something that had never happened before. After about 10–15 seconds, I released the key and applied a small throttle (1/4 to 1/2) before turning the key again. The engine cranked several times but eventually started, running roughly for only 20 seconds or less. After driving the vehicle, it runs normally under normal conditions. I’ve already completed a full tank of fuel and observed no change in fuel mileage. The problem persists intermittently: sometimes the truck starts on the first crank, other times it requires multiple attempts — regardless of whether it's cold or warm. Applying throttle during cranking reduces the number of cranks needed but does not eliminate the issue. I used a pocket OBD2 scanner and retrieved code P030-0 (random misfire). I cleared the code, but within five starts, it reappeared. Clearing the code again has not resolved the problem. I’ve already run fuel injector cleaner through the system and drained the tank at the onset of symptoms — the fuel tank was never run dry. Based on research into P0300 codes, I don’t believe this is related to exhaust systems or ignition components such as spark plugs or wires. Before proceeding with a full ignition tune-up or replacing the oxygen sensors or crankshaft position sensor, I’d like to know if there are any other potential causes. Any suggestions would be greatly appreciated. Thanks, Robert