Hello @mikejensen83 ,
from the network description the catalyst C4500-X is not directly connected to the two ISPs.
If you want one specific source IP to exit to the internet via ISP-2 this configuration needs to be performed on the firewall and it will be a combination of PBR and NAT.
The PBR configuration is local to the device where you configure it, even if you configure it on the C4500-X then the packet is passed to the firewall that is not aware of the PBR configuration on the switch and would try to NAT and send the packet via ISP-1 if you have a primary/backup strategy.
This is why you should work on the firewall directly:
a) packets sent to the firewall are for sure not with an internal destination if the C4500-X performs inter VLAN routing
b) the firewall in any case is the only device able to perform NAT that has to be performed accordingly to the chosen exit interface / internet next-hop.
Hope to help