I know my reply is way too late and so I apologize.
Mutare to Chimoio is mostly good condition with some roadworks near Chimoio. Chimoio to Inchope good tarmac. Inchope to Muxungue mostly good tarmac. Then Muxungue - Save - Pambarra (turn off to Vilanculos) has really bad sections, broken tarmac, potholes right across the road is some places.
So depart the border no later than 0800 to make Vilanculos before dark.