Muchen polled 30,841 votes to defeat Alams, the candidate of the Peoples Democratic Party, who scored 20,102 votes.
PDP now has 13, while APC has 10 in the 24-member House of Assembly.
One constituency seat is outstanding.
Executive Assistant to Governor Jonah Jang, Mr. Nyam Dareng, won in Jos South on the platform of the PDP as House spokesman, Mr. Diket Plang, also of the PDP, was defeated by a female APC candidate, Mrs. Alice Dimlong, by 17,028 to 16,134 votes.
Former Majority Leader, Daniel Dem, retained his Riyom Constituency seat under the umbrella of the PDP, while former Speaker, Caleb Mwansat, also of PDP, made it to the House for a second time.
Former Deputy Speaker, Baba Hassan, is also second time lucky, but this time on the platform of the APC.
He was in PDP when he vied for the Assembly seat for the first time.