A bad misfire.
Misfire (tune-up), vacuum leak are the minor things to look for without a engine light with engine light have it scanned and that should tell you, major things could be internal damage depending on if broke, it was ran low on oil or ran it hot....ect. Hope this helps
Looking for a Used Crown Victoria in your area?
CarGurus has 9 nationwide Crown Victoria listings and the tools to find you a great deal.
Search Ford Crown Victoria Questions
Ford Crown Victoria Experts
Related Models For Sale