P2A00 & P0300 Codes

Kmccarthy714

Whats up guys, as my title states i have a P2A00 code(which was on the car when i bought it) and recently since weather changed and got colder i throw a P0300 code.

I Bought the car with Stillen G3's and Stillen Catback exhaust, i assumed A/F sensor for the first code and installed it right after buying the car, i was wrong. After researching found it could be related to the intakes themselves or a air leak of sorts so i left it alone for a while until i could get to the tuner. Now i have throw this P0300 code to go along with the P2A00. Ive noticed my idle has gone up to about 1k with the random miss. Am I right in assuming both codes are related? and if so that they are either being related to the intakes themselves(not likely it would be both banks) or a vacuum leak on the intake side between the MAF and AF bank 1 sensor 1? Whats the easiest way to check for leaks, what is most common and what other things should i look for. Any help would be greatly appreciated.