Have you done a backflush through the motor of the car? I had a problem like that and it was that my motor had something clogged. After have my local radiator shop do it for me, my car ran just fine and didn't over heat.
http://www.mustangsandmore.com/ubb/FordRearDimensions.html Go here for the measurements you need for your rear end. You might want to ask a local shop that deals with Rear ends where you could get it done. It might be cheaper that way than shipping it. Good Luck
You know if they pass this it another step forward into trying to get our carrs off the road. Even though we don't have to pass smog, they will try to do something to our cars. I already emailed her and I already let her know how I feel.
BTW You know she drives a SUV.
How about just changing your jets. I had almost the same problem when I took off, it would flattened out. I went a step down on the jets and it sloved me problem. Also you might want to change the rods also. Just a suggestion