i just flashed my i9001 from 2.3.6 to [GT-I9001][ROM][ION][KK][4.4.2][KOT49H] CyanogenMod 11.0 by ADC-Team - Release 2 (ION) - Kernel 3.4.x
flashing looked normal. no problems. but now wifi drops out. especially when i open whatsapp. on instagram, facebook it works normal, no drop out. only with whatsapp.