I recently started getting P0300, P0301 thru 5, but not always misfires on all cylinders. (Each time they are set, I clear them, so I have 4 sets of codes) No other codes have been set, only P030x cylinder misfires. Starts with a sudden loss of power on acceleration, after driving maybe 3 to 7 miles. If I try to accelerate too much, the engine starts to die, but usually recovers as a let off the gas, with enough power to limp home. Last time P030x codes were set for all cylinders except #3. Once it died completely and couldn't be restarted until the next morning. Today, revving above 2k rpm would cause the engine to start dying. No popping, sputtering or backfiring is occurring, just loss of power.

Last winter, the fuel filter, vacuum lines, and MAF sensor were replaced and throttle body was cleaned as a result of various "lean" codes and stalling. Until recently ,the car was running fine.

I checked the distributor cap, wires, coil- all have about 50k miles, and tested the cam position sensor, and all looked good, though the problem is intermittent. When it's dark outside, I notice a faint glow on either side of the coil when the engine is under a load at idle, but I think this may be normal.

Is this misfire code always related to a ignition problem, or can it be related to a lack of fuel supply? Any suggestions would be greatly appreciated.

Thanks,
Kcarl