Ok guys so I'm new to the cobalt community, I picked up a 2006 cobalt ss/sc for 2000 dollars

Following mods:
Zzp long tube intake
Zzp 3.0 pulley
Zzp #42 injectors
Zzp dual pass end plate
Zzp cel down pipe
Zzp shorty header
Sickspeed oil catch can
Upgraded radiator
NGK iradium spark plugs
Custom HPtuner
Full magna flow CBE
GM stage 2
Ported polished supercharger
Otp front mount heat exchanger

But here is the issues I am having so far.

PROBLEM ONE
On cold start it surges idle. I've looked all over for a vacuum leak, and I can't find one

I've thoroughly cleaned the Tb twice (even used a damn toothbrush on butterfly joints)

Cleaned the MAF

removed and cleaned the injectors and checked o rings

PROBLEM TWO
Misfires at idle. Throws a random misfire code. If I reset the ecu by unplugging the batter than it will clear the code and not return for a day or so.
But the surge idle is getting way worse. The car will stall out randomly at idle.

I have a wideband that is reading 19.1 AFR to 13.6 it jumps back and forth. I'm not sure if I can trust the wideband because I'm not getting white smoke, and I'm actually getting black smoke(once I hit rev limit) and it smells a bit rich.

I changed the spark plugs recently and no help. I also checked the timing chain thinking it jumped a tooth or possibly a bad timing chain tensioner, but it was good also.

I'm clueless guys.

 

get the tune checked and retuned if needed

 

check the tune but try getting a new OEM MAF and get the maf table re-done in the tune.

 

OK so update on the problem. It is "kinda" a vacuum leak. My injectors are having a hard time sealing. It is causing a vacuum leak and I think it is the injector insulator. But what I'm asking about is on the end of the injectors in pictures I've seen.. There is a white piece in front of the bottom o ring. The one going to the block not the fuel rail. Well my injectors do not have those. Are those white pieces there to help the o ring seal on the insulator?