SNAT/NAT does not work. It changes src and dst ports

Can you provide both the SNAT pool configs? This is how I would do copy the config to a note pad and then do a find replace and sanitize the ip's use dummy ones. So what you are saying is first pool works fine and the 2nd SNAT pool does not? If bigip changes ports it would store it in its routing table and will change it back unless I am missing something here.