A couple of questions. Do you have an aftermarket CAI? Did you clean the throttle body when doing the install? Did you check all of the vent tubes for proper reattachment? Did you torque the new manifold bolts to spec? Finally, did you use any gasket compound to seal the insulators?
Okay, maybe a FEW questions.
OGOC (Ontario G8 Owners Club)
09 PBM V6 (Traded)
GXP Diffuser, Mace Insulators, Solo, CAI, FE3, BMR, much more
09 WH GT, Solo Mach, HF Cats, CAI, LS3 Cam, Pat G Tuned, FE3, Whiteline, SuperPro, Centric/Hawk, DAI Autobahns 19x8.5/+35, RE760s