Ok I have a98 gtp 2001 Bonneville motor. I have a 3.4 pulley, power log,3"catless dp, NGK TR6 gapped @.50,cai reptiles tune, car ran prefect before I installed #90 springs modified retainers and zzp1.9 rockers. I dive it daily, no check engine lights no misfire coming up on torque app, 3*kr new plug wires..car will idol fine run, give it lil gas about 1/3 to 1/2 throttle it will kinda chug n poo kinda sounds like backfire through intake like some one using an empty 5 gallon bucket as a drum kinda what this popping chugging noise is if I floor it will pop n chug n get through it then it halls ass new rocker bolts torqued accordingly Also. If I'm driving with cruise on going up hill it will do it a lil bit also some times it may not do it at all I dive 75 miles a day only code I get is for evap system please help
Galaxy S5