* It's a typo or misremembering: The term might be similar to an actual code or abbreviation used by Ford, a dealer, or a repair shop.
* It's an unofficial term: A specific dealership or repair facility might have used "RAP" internally for something related to the 2000 Explorer.
* It refers to a specific feature or package: It's possible "RAP" is slang or an abbreviation for a particular option package or feature offered on that model year.
To find out what "RAP" refers to, you'd need more context. Where did you encounter this term? Knowing the source might help determine its meaning.
