Did anyone else catch this? I don't know the actor's name but here are the three episodes in question:

(1) He plays a guy a year older than Greg who sells Greg the old junked out jalopy of a car.

(2) He's a college freshman while Greg is in high school, and tries to convince Greg to move in with him because he needs a roommate.

And in a completely separate role,

(3) He's the quarterback of the opposing team (same age as Greg) who steal's Greg's playbook from his house while he pretends to be dating Marcia.

It was Chris Beaumont, and he was in 4 episodes:

http://www.imdb.com/name/nm1938945/

YES!!! Chris Beaumont is a legend! "Hey there, what'cha reading?" Classy! Too bad it didn't work out so well for Greg later in that episode, haha! Jerry Rogers was of course his most memorable performance, but I always loved the line mentioned above in the episode "Our Son, The Man."