Q: Lost of power and will only go 40 mph and 15 mph up hill.

Hi there. Check the vehicle engine out to see if there is anything out of the ordinary. The loss of power could be a vacuum leak, misfire, or a transmission issue. First look for any vacuum lines that are cracked or missing. Then check to see if the engine is shaking. If the engine is shaking, then there could be a misfire caused by a fouled spark plug or a failed or dirty fuel injector. If the fuel filter has not been changed in a long time, then I recommend replacing the fuel filter as it may slow down the fuel delivery and cause the engine to have a loss of power when loaded. If you need further assistance with your engine having a loss of power, then seek out a professional, such as one from Your Mechanic, to help you.