Had this issue for quite some time now; seems to be more prominent with the CAI - and during cold mornings.
I'm relatively sure it's the car hitting boost cut (or fuel cut? I do have a walbro fuelpump and yellowtop injectors to my belief) as my mechanical boost controller spikes a hell-of-alot during cold mornings/nights - but the problem I have seems to diminish during slightly warmer weather.
What tends to happen (and moreso when hitting full boost in 3rd gear than any other gear) is the motor seems not to be attaining ample fuel/air; causing a subtle jerk and feels asif it's trying to make riddance of perhaps unburnt fuel out the exhaust. You'll find that some backfiring occurs, accompanied by a popping sound that generally comes from the vicinity of the exhaust. Perhaps it's a detonation issue. I'm really not sure.
I've tried turning down my boost, but it makes the turbo laggy as hell - so i'm thinking of re-attaching it to the stock boost solenoid, because I'm sick of trying to pull in any gears - and it honestly feels asif the spark is being retarded. Maybe it's an ignition issue? I am absolutely perplexed.
I'm running no
BOV so perhaps turbulent air recirculating upon the closure of the throttle body is playing games with my AFM. I might get some contact cleaner to the AFM this weekend and see if it changes anything.
Any enlightenment would be appreciated, as it's really got me scratching my head!
Cheers.