This has been bugging me for a while because I remember this show vividly AND I finally found it: The Ultimate Impostor link bonus: it stars Erin Gray!

He's a spy who had his memory erased by the Russians and now they can program him with knowledge but it only lasts 72 hours.

 

@user13649: The Oscar Goldman reference above was a show called The Delphi Bureau - about a guy with a photographic memory.

This has been bugging me for a while because I remember this show vividly AND I finally found it: The Ultimate Impostor

bonus: it stars Erin Gray!

He's a spy who had his memory erased by the Russians and now they can program him with knowledge but it only lasts 72 hours. 

@user13649: The Oscar Goldman reference above was a show called The Delphi Bureau - about a guy with a photographic memory.