1999 GMC Yukon Gas

Hello. My truck is not takin the gas properly. U can press the gas but its still pickup real slow. Plus u can drive it for awhile an it will just cut off. Truck will start right back up but will not have much press. U might can go up to 20 mph or less. I had the truck service complete. I changed the gas filter. The filter was stopped up. Now the truck is still cuttin off. Could u plz tell me what that could b