The Brazilian came off the bench midway through the second half to replace Jonathan Urretaviscaya and 17 minutes from time he struck to ensure the hosts remained unbeaten since August.
Estoril had earlier led through Ruben Fernandes' header, but they were wasteful in front of goal and in the end were left hanging on for their point, meaning they have now won only once in their past nine matches in all competitions.
The hosts threatened first when Bruno Moreira dragged a right-footed shot narrowly wide with Pawel Kieszek rooted to the spot, but it was Estoril who twice came closest to breaking the deadlock as the opening half drew to a close.
Kuca found the side netting, before Fernandes sprung the offside trap, but when clean through he could only hit a tame effort too close to Rafael Defendi.
Fernandes atoned for that miss four minutes after the restart, though, getting on the end of Toze's left-wing cross and planting a header across Defendi and into the net.
Kleber ought to have doubled the visitors' advantage in the 65th minute, but he placed his shot wide of goal after being played in one-on-one.
That miss proved costly eight minutes later as Paraiba twisted and turned his way inside the area before firing beyond Kieszek into the bottom left-hand corner to extend his side's strong run of form.