Mouamba was born in late 1943 or early 1944 in Sibiti. Under President Pascal Lissouba, he was Minister of Finance from September 1992 to June 1993. Mouamba was a leading member of the Pan-African Union for Social Democracy (UPADS), which was the ruling party under Lissouba and went into opposition after Lissouba's ouster in the 1997 civil war.