I am a young male, i am been having stomach issues and a lot fatigue for quite sometime, my a/g ratio came back high at 3.0. everything else is normal. do it have a liver or kidney disease? or a intestinal disease? what can cause this?

You slightly elevated A/G ratio is non diagnostic for kidney or liver disease in the context of stomach issues and fatigue and work up has to continue. There is limited use otherwise of a high A/G ratio, seen sometimes in immunodeficiencies and/or malnutrition.

Protein A/G ratio and values depend on many things which should be taken into consideration. Also the accuracy of the test. If your liver enzymes and urine protein is normal then there is very great chance it is not from them. You need a good clinical and Lab evaluation by an internist. Wish you well.