History of myocarditis + chf (30&8yyrs ago). feel shortness of breth&othr symp. Cardiac enzymes OK. Jgb, hct, rbc low but not bad. Can this be myocarditis?

Myocarditis. If your cardiac enzymes are normal it is unlikely. A CXR and an echo may be helpful to complete your assessment. The anemia may be unrelated and should be looked at separately. All the best.
Yes. Yes with a history of myocarditis in the past this entitiy can recurr. In addition it can also lead to congestive heart failure which can also cause shortness of breath. The best course of action is too see a medical practioner and be evaluated.
Heart failure. You have symptoms of heart failure which is likely cause by residual damage to your heart from your previously diagnosed myocarditis. You need to be followed up by your cardiologist who can guide you to the next step in your management granting that all these years you have been on active treatment from the time of your diagnosis.