Is it a 4x4? Extended cab? If so, I'd say you got a deal. I recently bought a '98 XLT 4x4 ext cab with 69K kms & I paid $22,800. I shopped hard for that truck and it was a great deal. So if you got one a year newer for less than $20k, you did OK.
The 4.6 is a great engine. Don't go trying to pull your 10,000 lb horse trailer around with it or anything, but I find mine plenty powerful enough and still reasonable on gas ( just over 20 mpg Hwy). Search out info on this site, there's tons of it. Good luck..