Some more info on this: the logfiles indicate that the IdleRemover thread seems to get stuck. After some time, we don't see the "IdleRemover notifying pools" message any more.
After some more time, threads requesting connections from a pool get a "ResourceException: Interrupted while requesting permit! Waited 0 ms". Then, the IdleRemover thread continues one more round, but get stuck again.
Can you retest with a later version of JBoss?