People are going to need more information then what you provided to diagnose your issue. Wrong injector data, improperly seated injectors, and just a messed up plug or coil could all cause what you have described. Is your misfire just at idle? Does it happen at wot? How many misfires are you reading? Where did you get your tune from?

 

injectors are new plug are new I changed coil in all position and always misfire on #3 cylinder.. just misfire at idle nothing during I drive.. I read 18-20 misfires... its a bad tune for my car? or air leak between sc and manifold intake?

 

can be my cat? I see wool exhaust in my garage ... my exhaust can be clogged and causing misfire?

 

I see that in my garage? can I have porblem with my cat or resonator? and causing misfire?

 

update im back to gm stage 2 and only 2 misfire at idle after 1 minutes on idle...

 

This misfire at idle has gone on for 6 months plus. I can't get my LNF inspected and risk getting stopped, although suppose would get a permit to extend inspection time.
The plugs have been changed three times, 1) older Iridium GMs replaced with 2) IDK cooler range, then 3) back to stock GM iridium's.
Then I tried replacing a found to be bad ign coil.
Then wound up buying the hot looking ZZP coils all four.
I wonder if it is a short to ground in those wires behind the driver side headlight?
I have not had a problem with a detectable misfire you could feel since replacement of that one coil over cyl 4.
Yet I must locate the culprit, and do not think two local dealers will help-as my mods will send them through the roof. Hahn intercooler, cross piping, downpipe, no cat, SRI from Dejon and external blow-off valve with capped recirculation at turbo flange.
The thing has great functionality and puts 315 horses to the wheels. It just baffles me.

 

My tune has not changed it is a rather rich one from Trifecta...