Can mono (which I had 9years ago) still afect Alt and Ast? Constatly higher but a liver ultrasound and blood test is always normal.

Not clear. ALT and AST are enzymes which are measured in the blood and you say they are aolways normal and higher simultaneously. While they are produced by the liver they are also produced by other organs. You should see a good internest.
Definitely unusual. I am sure your doctor tested you for hepatitis A, B, and C, and told you to abstain and avoid medications that might cause this. Ask your doctor if liver biopsy could be useful in arriving at a more accurate diagnosis.