2001 Mitsubishi Eclipse Spyder GT Misfire P0301

The car is a 2001 Mitsubishi Eclipse Spyder GT, 3.0L V6. 103xxx miles.

Hey fellas, about a week ago, I have put premium fuel instead of regular and then my car started acting up about two days later. It would sputter, and feel like it was running on 5 cylinders instead of 6. This would happen under load, at low rpms or high. Now, this would be constant. So, I changed the wires and plugs, and now the problem comes and goes. It threw a P0301, misfire in cylinder 1, would this lead to my rotor cap and distributor, since I already swapped out my plugs and wires? Anyway, my buddy erased the code, earlier today, and it hasnt came back on, car runs fine, but once I take it up to rpms around 5-7k, it starts spitting and sputtering, which it never did before. Overall it feels like it lost power, runs like a 5 cylinder car instead of 6. Car did run rich prior to plug/wires change, now it runs fine, still P0301 exists. The car idles fine, its just when I'm driving it, sometimes it will sputter for a bit when under load, then go away and not come back....sometimes it will stay. So weird.

I've never had problem with this car either, it has always ran like a champ. Computer was recently replaced on it, plugs, wires, coils...could be injector, dont see why it would be a O2 sensor, a different code should pop up. Catalytic converted should be fine too, no smell or anything.

Help me out, guys, I dont want to throw any money out there for nothing. Should I get that rotor cap and distributor?

Thanks in advance!

Hi I have the same problem witch my Eclipse G3 3.0L. I change the wires/spark plug/cap distributor and rotot but broblem was staying. 2 days lather i verifying timing belts marker on camshaft and crankshafts - All OK.
After 5 days I payd the new distributor assy and install them then nothing change.
Go to the workshop and payd a new Camshaft Position Sensor and now installed on engine. Switch IG ON and chech lamp lights off. Run scanner and looks DTC item. No Errors. My problems lets go away.
Sorry my Eng.