Pakistan seems to have been overly preoccupied with 3 of its 4 neighbors. Pak Cheen dosti, India Pakistan sibling rivalry, and Afghanistan - the neighbor you wished you never had.
Iran - Pakistan headlines in the papers are scarce. Perhaps the only time you hear about Iran is when it comes to the IPI or IP gas pipeline. Or to a much lesser extent - when Iran also does something to counter its own Baloch insurgency.
Is the lack of cooperation between Iran and Pakistan - mostly the result of Shia/Sunni issues?