Good day everyone,in search of done help Subaru Legacy blitzen,was doing a little pull the other night noticed a jerking when boost reaching 1 bar like car was stuttering,that happened before when I had in normal ngk spark plugs that needed changing,changed to denso vk20 was running good.now the guage light up do its normal cycle then sticks in one spot and at morning cold start is rough almost like the car wants to stall then it drives normally boosting I would say normal,any help would be appreciated