Rpms wont go past 3000 and car wont go faster than 40 mph

I'm not sure about the system in your car, but this sounds like it may be stuck in "limp home" mode, where then engine detects a fault and limits the cars speed and rpms to protect the engine from any further damage. I suggest you check the throttle body and you can find instructions online that will tell you how to tell if it is in limp home mode, and possibly how to fix it yourself., Although if limp home mode did engage, there may be a more serious problem with the car, and i suggest you have a mechanic look at it.