If Im not mistaken from your description you have two defaults routes in your network and have certain internat IP subnets to be directed to another default route other than the ASA default. ASA only supports one default route, so what you are trying to do is PBR which currently is not supported in PIX/ASA as of now.
What you may want to do is do the pbr from an inside router behind the ASA for accomplishing a next hop default route.
It will follow the ASA default route..for example http traffic, to tell the asa to send outboud http traffic from specific inside network nated to another asa external interface for http it is still a PBR function, http traffic will go asa outside interface or whicever the default route points to.
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...