help with these codes

[tx02]

i recently purchased an 02 Boxster S and have a few questions on the direction im about to go.


I had a CEL come on and had a buddy read the codes....0507,0446,1128,and 1130.
The day i got the car, the CEL came on. Stopped to get gas, and after filling up it wouldn't start. It would turn over just fine, but wouldn't start. Finally after sitting a bit it started. It was making that "humming" sound coming from the gas cap/filler area. When you gave it gas, the humming went away. I saw a video on Pelican Parts about it probably being the purge valve, so i replaced it with a new one but still makes the noise. My gas cap is not in the best of shape, so i ordered a new one.

Now what I've got going on is when its first started and until its good and warmed up, its sporadically missing and backfiring.
ive done some searches and research on here and a few people have had luck wit cleaning the throttle body and MAF when they had 2 of those codes, so im going to try that. Also purchased a new air filter to change out while im doing this (i have no idea what shape the one that's in it is). I figured it cant hurt.
I also have been reading today about the Idle Air Control Valve, and wonder if this could be part of the problem.
I am not sure if those are cleaned or replaced. If anyone can chime in id appreciate it. I looked on pelican parts and couldn't find the IACV in case i have to buy one.

any help will be appreciated