It looks like 0300 which is Random Missfire which kind of goes with what you said...
I am no expert but I found the following
Hopefully someone a lot more knowledgable can help
DTC P0300 - P0306 MULTIPLE CYLINDER MISFIRE, NO. 1 - 6 CYLINDER MISFIRE
On Board Diagnosis Logic
When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the crankshaft
position (CKP) sensor (POS) signal to vary, ECM can determine that a misfire is occurring.
The misfire detection logic consists of the following two conditions.
1. One Trip Detection Logic (Three Way Catalyst Damage)
On the first trip that a misfire condition occurs that can damage the three way catalyst (TWC) due to overheating,
the MIL will blink.
When a misfire condition occurs, the ECM monitors the CKP sensor signal every 200 engine revolutions for a change.
When the misfire condition decreases to a level that will not damage the TWC, the MIL will turn off.
If another misfire condition occurs that can damage the TWC on a second trip, the MIL will blink.
When the misfire condition decreases to a level that will not damage the TWC, the MIL will remain on. If another misfire condition occurs that can damage the TWC, the MIL will begin to blink again.
2. Two Trip Detection Logic (Exhaust quality deterioration)
For misfire conditions that will not damage the TWC (but will affect vehicle emissions), the MIL will only light when the misfire is detected on a second trip. During this condition, the ECM monitors the CKP sensor signal every 1,000 engine revolutions.
A misfire malfunction can be detected on any one cylinder or on multiple cylinders.
DTC No. Trouble diagnosis name DTC detecting condition Possible cause P0300
P0300
Multiple cylinder misfire detected
Multiple cylinder misfire.
Improper spark plug
Insufficient compression
Incorrect fuel pressure
The injector circuit is open or shorted
Fuel injectors
Intake air leak
The ignition signal circuit is open or shorted
Lack of fuel
Signal plate
Heated oxygen sensor 1
Incorrect PCV hose connection