Question: I have a German passport and would like to travel through Iran to Pakistan and then back to Turkey through Iran again. Could you offer help about whether this seems feasible?
How big is the chance I am granted another visa in Pakistan if I say I want to travel back overland?

Answer: Since no double entry visa is issued for Iran so you can apply for your visa through an agency and get a visa stamped in your passport for your one entry and then an on arrival one at the airport for the other entry.

For Iran visa check: http://www.uppersia.com/Iran-travel-services/iran-visa.html

Check the cheapest Iran tours at http://www.uppersia.com/Iran-tours