why does my car not drive when it gets hot or its hot outside? on 1999 Mercury Cougar

My car has an aftermarket alarm with auto start...When it gets hot(the car, from driving) or its hot outside the car loses power and doesnt want to start.If you hit the auto start itll power up but not stay running...I thnk its wired in correctly...Any thoughts? I dont even know where to ask a mechanic to begin...

Asked by for the 1999 Mercury Cougar