Your suspicions are right on target! The Greek infinitive is used to
express various concepts: temporal, causal, and purpose, depending on
the particular construction with which it is used.
prin (h) + inf. = the temporal idea of "before"
pro (tou) + inf. = " " " " "
en tw + inf. = " " " " "while"
meta to + inf. = " " " " "after"
eis to + inf. = shows purpose = "in order that"
dia to + inf. = expresses the causal idea - "since, or because"
kai egeneto + inf. = " " " " - "that"
The "tou fugein" of Jonah 1:3 is yet another way of expressing purpose
(besides eis to + inf.), and means "in order to."
Wayne Price