Hey, I was wondering if my Heracross’ Attack (who has Guts) would still be boosted after I cure his status condition, say, sleeping or paralysis.
While a Pokémon with [Guts] has a status condition, its Attack is increased by 50%.
Source
According to Bulbapedia's description, Guts only boosts attack if the Pokémon is inflicted with a status condition, so there is no attack boost if the status condition was removed. For instance, in this battle, Heracross's Megahorn was 65% stronger when it was burned than when it wasn't.