denaliprocharger6.2

I have a 2008 gmc denali sierra 6.2 L
i have just put on a pro charger, and have taken the truck into where it was tuned several times and still isn't running quite right.
in neutral if i slowly raise the rpms the truck starts to sputter. and i thought it was only at low rpms. which made my tuner guy tell me that its the MAF sensor was reading the excess air bouncing off the throttle plate back and forth across MAf sensor and not to worry.
But i have an electric exhaust cut out on my truck and with it open i can notice the sputter all through the rpms even at 5000-6000rpm.

So getting to my question, when the bigger fuel injectors were installed they came with spacers to raise the fuel rail just a little bit higher because of the taller fuel injectors.(thin washers). I never put those spacers in because i was getting leakage around the injectors. but with out these spacers these injectors are quite snug in there.
im not sure how it all works but i was wondering if maybe having the injectors snug in the fuel rail if maybe it isn't able to fuel itself properly?
Is there any harm in having the injectors tight so you can't wiggle them very easily?

AKlowriderZ71

iTrader: (22)

What injectors were installed?

Mangled03gmc

iTrader: (95)

Yes, we need more info on the set up..