I currently hAVE A 1999 F150. I know repair history on it. Im looking at a 2003 this weekend. Guy bought it off another individual. he doesn't have repair history. How worried should I be about the spark plug issue

 

If you are talking about the broken plugs, that was the 3V version - and a 2003 won't have that issue. If you are talking about the plugs that blow out, 2003 will be the best version of the head for that issue.

I personally wouldn't be concerned just from the info you've given.

 

I would be more concerned about issues you do in fact have versus the ones you don't or might possibly maybe get...