I have a 1998 Ford Mustang GT with a 2005 Crown Vic engine. The car was running flawless when I parked it one night. The next morning I went too start it and it barely starts up. Battery and alternator are good. Once it starts running it runs really rough and will shut off if I touch the throttle at all. It’s almost like it is losing vacuum. Is there any specific places I should be looking for leaks or what is the easiest way to find the leak?