hello,
i have replace the head gasket on my 05 monte carlo 3.4 eng. i have receive some new codes since the replacement. P0101, P0108, P0340. please advise

 

Quick google search shows MAF sensor, MAP sensor, and cam position sensor.

That's a ton of stuff going on to be able to accurately diagnose remotely. You'll need to get a scan tool and read what the sensors are showing

Are you sure all the wiring is hooked back up right? Are you sure all the grounds are hooked up? Any vacuum leaks?