The Vivacom Rally Team Skoda driver was quickest on stages three, four and five to build the lead in hot conditions. Krum Donchev won stage two.
Peugeot driver Gyoshev, 19.4 seconds adrift after that morning loop, hit back with wins on stages seven and eight, but Iliev reaffirmed his position on the last.
Gyoshev is more than two minutes ahead of Todor Slavov as local drivers occupy the top three positions.
Iliev has won the asphalt rally five times before. This is the first time it has been held as part of the IRC, although the top drivers are giving it a miss.
Yagiz Avci, the winner of the previous Intercontinental Rally Challenge round in Ukraine, is fourth.