24 hour urine catecholamine for a pheo- if a person does not have an episode during the 24 hours would it still show elevated levels. If so how?

Usually, yes. A pheo usually secretes catecholamines continuously, so it is not usually necessary to time the collection. These catecholamines yield a lot of breakdown products (eg. metanephrines). However, in some circumstances, if there is a very high suspicion for pheo and the initial tests are negative, and the attacks are sporadic, a urine collection timed with the episode is reasonable.