In 16 minutes, both Dennis Mukaisi and Otieno had tested Muhoroni Youth custodian Salim Sowedi in vain.
Gerson Likono’s free kick outside the 18-yard box veered off the target in the 32nd minute.
Muhoroni never looked comfortable as Rangers pinned them to their own half.
Their only clear chance in the first half came in the 38th minute. Yusuf Mohammed unleashed a left-footed drive from a 25-yard free kick that Patrick Matasi collected easily.
Three minutes to the break, Titus Achesa was given space to meander in-field, passed the ball to Likono who passed back only for the former Nakuru AllStars man only to see his shot deflected for a fruitless corner.
Likono cut in at the hour mark from the left flank but scooped his shot direct to Ugandan custodian Sowedi.
Pamzo pushed numbers in attack by introducing Nairuka and Jared Obwoge for Mwaura and Otieno in the 52nd and 70th minutes respectively.
Nairuka had his 81st minute free kick from the right headed wide off target by Jockins Atudo. Mukaisi thought to have broken the deadlock in the 86th minute but his header ricocheted off the bar much to the chagrin of Posta fans.