Will not go more than 40 MPH

Hello, I'm Danny.

It sounds like your car may be in "limp" mode due to a engine code or fault due to a failure of some sort. Is the check engine light on or flashing on the dash? What we ask you to do is perform a CAN scan to retrieve all code information from your car. A CAN scan will test all the systems on your car. Here is a tutorial showing what is involved for a CAN scan:

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

After performing this procedure get back to us with all stored code information and then we can properly diagnose these issues with your car. Hope this helps and thanks for using 2CarPros.