Originally Posted by Chuck33079

OP, start by cleaning your MAFs and throttle bodies, including the connections. Double check that you've installed the intakes correctly. If the code comes back without a corresponding misfire code of an individual cylinder, then start replacing parts.

P0300 is a huge pain in the ***. It's way too general, so it does no good as a DTC. My tuner ended up turning it off since my flywheel rattled enough for the ECU to think I was misfiring.