1999 GMC Suburban Engine stalls when press on gass

I shipped my GMC to germany from the states when I drop it off everything was find then when it got to germany I fueled up and about 1hr later the truck cuts off, about every 10mins I had to pull over turn the truck off then turn it back on you it will go above 1,000RPM I change the O2 sensor then it was better for about 30mins then started stalling again since then I have change the distributor cap, plugs&wires, Cataylic converter and I new set or O2 sensors again it was working fine then it starts to stall again after a few min. And it also its popping from the air filter. OBD II reads code UNKNOWN. I also replace the fuel filter. And before I sent it to germany a new fuel pump was installed