Opener Imran Farhat (41) and Mohammad Yousuf (six) were unbeaten at the break after Pakistan lost opener Mohammad Hafeez (18) and Younis Khan (20) in a sluggish first session on Monday.
Yousuf, who hit a match-winning 192 in the first Test in Lahore and a match-saving 191 in the second at Multan, needs another 143 runs to break West Indian Vivian Richard's world record of most runs in a calendar year.
In 1976 Richards hit 1,710 runs in 11 Tests.
Left-hander Farhat put on 26 for the first wicket with Mohammad Hafeez and faced no problems after Pakistan won the toss on a good batting pitch before fast bowler Corey Collymore provided the tourists with the breakthrough.
Hafeez was beaten between bat and pad and was bowled for 18.
Younis, who looked out of sorts and edged between slips early on, took his first run after six overs before failing to beat a sharp throw from Daren Powell on his follow-through and was run out for 20.
Farhat, who hit two fifties in the second Test, has so far hit seven boundaries and looked in great touch.
The West Indies brought back their vice captain Ramnaresh Sarwan in place of spinner Dave Mohammed from their line-up in the second Test, which ended in a draw at Multan.
Pakistan, who won the first Test by nine wickets in Lahore, kept the same side for the second Test running, resisting the temptation to bring back frontline paceman Mohammad Sami.
Pakistan 88 for 2 (Imran Farhat 41, Younis Khan 20, Mohd Yousuf 6 n o; Collymore 1 for 17) Vs West Indies