Let me start from the beginning. So, about two weeks before christmas, I replaced my spark plugs, wires, valve cover gaskets and intake plenum gasket. While doing this, I noticed that the timing belt was starting to crack. It got ignored at the moment and everything went back together and the car ran normally. Then the day before christmas eve(wednesday), I got my timing belt done with a kit that include the belt, water pump, etc. Car ran fine after it was done. Then I didn't drive it until the following monday. On the way to work it drove fine, but starting it when leaving, it started misfiring and giving P0300 code. It was running rough, there was a big loss in power, and it sounded very off. Then I put in a new distributor cap and rotor cause I noticed it looked original. After this, the idle returned to normal and the code went away until I revved it a little. The code came back up when it was revving back down to idle. So I cleared the code and checked the data stream. The only thing that I could tell was off was that short term fuel trim bank one was 18 and short term fuel trim bank two was at -18. Long term fuel trims were around the same. Then, I revved it and the code came back on and the rough idle came back. The only thing that had changed between the normal idle and the rough idle was at normal idle, the MAF sensor was reading between 6.00 and 6.30, and at rough idle, it was reading between 3.5 and 4. What would cause the rough idle and loss of power to come back and how do I fix it?