@richs53 Hello and welcome to Mayo Connect and our MAC & Bronchiectasis support group.
As a 6 year member, and one who has been through the antibiotic regimen, I can tell you there are no absolute foods to avoid.
MAC is different for each of us, and we come here with a few, some, or many other health conditions as well. Some people had GERD (reflux) and need to avoid foods which trigger it. Others have food allergies, and must avoid certain things no matter whether they have MAC or not. Some people think milk or dairy products thicken their mucus and avoid them (science is limited on this - it comes originally from ancient Chinese medical literature, but modern studies do not support this. On the other hand, if you are lactose intolerant or allergic to casein or milk protein, it makes sense to avoid it.
When I was on antibiotics, I could not tolerate cooked tomatoes in any form - they left a terrible metallic taste that could linger for many minutes - but fresh off the vine ones were fine. And my stomach was often queasy, so spicy foods and meats were difficult. My appetite was poor (due to the queasiness?) so I ate/drank many protein and calorie rich mini-meals - protein-loaded smoothies, extra-rich ice cream or full-fat Greek yogurt with fruit & pumpkin seeds, cashews, cheese chunks. And at least one ounce of very dark chocolate a day.
Are you finding certain foods to cause any problems?

Also, though the research is mixed on probiotic supplements, I found it helpful to maintaining my intestinal flora to eat live-culture yogurt, fresh sauerkraut, pickles or kimchi and to take a multi-type probiotic.

Have you been advised to avoid any specific foods?