I HATE this stupid car...ugh!

Well, i'm supposed to keep you guys up to date on my engine code process and high idle problems....so, here we go.

The P0420 code is taken care of: Catalyst Efficiency Below Threshold (bank 1)
My MILs took care of that one

The P1507 code is also taken care of: Manf. Cntrl Veh. Spd. Idle Speed Control "Auxiliary Inputs"
My new IAC took care of that

So, I go to advance auto today to see my buddy and have him re-read everything....it comes up that NOT ONE code is showing, so i'm like SWEET and drive off....

Keep in mind that my TERRIBLE idle was still in full effect, hopping all over the place and all that good stuff, sagging rpms, LOVELY stuff.....

About half way home my check engine comes on....ok, w/e i'll just go back and have him pull it, he pulls it, and it comes up as this:

P0300 Random/Multiple cylinder Misfire Detection

Guys, i'm at the end of the road with frustration....ugh....any suggestions?

My friend and I are going to look at it this weekend....he is a mechanic with alot of diagnostic and compression tools....i dunno guys, i'm just really stressed out with it, maybe it is just a pulley or something, I DO have steeda underdrives on it, and to answer the question, the misfire is mainly in the lower rpms, the car sounds like it has a HUGE set of cams in it, and all of the rpms hang...i dunno....ANY help or suggestions though......yea you know.....blah

Big shout out to SVTtech76....you've been a big help bro

UDTBADkarma....if i find out what this **** is....i'll let you know!!!