How to Configure Cisco ASA 5512 for multiple public IP interfaces

Question

Hi
I have a new ASA 5512 that I would like to configure for multiple public IP support.  My problem may be basic but I am an occasional router admin and don't touch this stuff enough to retain everything I have learned.
Here is my concept.    We have a very basic network setup using three different ISPs that are currently running with cheap routers for internet access.  We use these networks to open up access for Sales to demo different products that use a lot of bandwidth (why we have three)
I wanted to use the 5512 to consolidate the ISPs so we are using one router to manage the connections.  I have installed an add on license that allows multiple outside interfaces along with a number of other features.
Outside Networks (I've changed the IPs for security purposes)
Outside1 E 0/0 : 74.55.55.210  255.255.255.240 gateway 74.55.55.222
Outside2 E 0/2: 50.241.134.220 255.255.248 gateway 50.241.134.222
Inside1 : E 0/1 192.168.255.1 255.255.248.0
Inside2 : E 0/3 172.16.255.1 255.255.248.0
My goal is to have Inside 1 route all internet traffic using Outside1 and Inside 2 to use Outside2.    The problem is I can't seem to do this. I can get inside 1 to use outside 1 but Inside2 uses Outside 1 as well.
I tried adding static routes on Outside2 to have all 172.16.248.0/21 traffic use gateway 50.241.134.222 but that doesn't seem to work.   
I can post my config up as needed.  I am not well versed in Cisco CLI, I've been using the ASDM 7.1 app.  My ASA 5512 is at 9.1.   
Thanks in advance for the suggestions/help

Answer 1

I have been away for a while and am just getting caught up on some posts. so my apology for a delayed response.
I find the response very puzzling. It begins by proclaiming that to achieve the objective we must use Policy Based Routing. But then in the suggested configuration there is no PBR. What it gives us is two OSPF processes using one process for each of the public address ranges and with some strange distribute list which uses a route map. I am not clear what exactly it is that this should accomplish and do not see how it contributes to having one group of users use one specific ISP and the other group of users use the other ISP>
To the original poster
It seems to me that you have chosen the wrong device to implement the edge function of your network. The ASA is a good firewall and it does some routing things. But fundamentally it is not a router. And to achieve what you want were a group of users will use a specified ISP and the other group of users will use the other ISP you really need a router. You want to control outbound traffic based on the source of the traffic, and that is a classic situation where PBR is the ideal solution. But the ASA does not do PBR.
HTH
Rick