were there any achievements of the former king mentioned?
He minted coinage as a sole king.
Antiochus XI Epiphanes
Philip I did not take residence in the capital and AntiochusXI minted coinage as a sole king. 
who is antiochus xi epiphanes? A Seleucid monarch who reigned as King of Syria when did he reign? Between 94 and 93 BC did any other king succeeded after him? AntiochusX
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Antiochus XI Epiphanes [SEP] Avenging Seleucus VI and taking the capital
The material evidence for AntiochusXI's success in taking the capital was provided in 1912, when an account of a coin struck by him in Antioch was published. Philip I did not take residence in the capital and AntiochusXI minted coinage as a sole king. PhilipI kept the royal title while remaining in the city which was his base during the preparations to avenge SeleucusVI. The numismatist Edward Theodore Newell assigned AntiochusXI a reign of a few weeks in the capital, but according to the numismatist Oliver Hoover, estimating the average annual die usage rate of the King suggests a reign of several months.