Always a good idea to disconnect the battery when installing anything electrical. One, reduces risk, two, resets DME. It's very easy...10mm socket and disconnect negative terminal in the trunk.
First...take logs and see what your trims, AFR, and fuel pressures look like.
Second, swap coil packs and see if the problem follows. If it does, change coil packs, if it doesn't...
Third, swap plugs and see if the problem follows. If it does, new plugs, if it doesn't...
Forth, swap injectors.....
2008 AW E88 Auto
Current--AA FMIC--Running 100% E85 on my flash tune--BMS CP, DCIs, & OCC--M3 FSB, RCAs, & FCAs--ER OC--Fuelab IFP, FPR, & FF, and E85 CP injection--RB PCV--Whiteline RSFBs, and DBs--ER SS brakelines--Stoptech slotted rotors w/Ferodo pads--Apex Arc 8s w/Nitto NT05's--Wavetrac LSD -- Waiting on install: Rogue toe arms and Ohlins R&T