Kitchen broke a tie in the 70th minute, scoring on a header off a corner kick.
DeLeon opened the scoring in the 54th minute, and Luke Moore tied in the 60th.
Bradley had a good scoring chance in the 34th minute, but the U.S. midfielder's shot went wide.
United improved to 8-5-4, and Toronto dropped to 6-5-3.
WHITECAPS 1, SOUNDERS 0
Sebastian Fernandez scored on a long shot in the 12th minute in Vancouver's victory over Seattle.
Fernandez took a pass from Pedro Morales and launched a shot about 30 yards out that sailed past goalkeeper Stefan Frei. It was Vancouver's first goal since June 7, ending a two-game scoring drought.
Major League Soccer-leading Seattle dropped to 11-3-3 with the loss that snapped its winning streak at three games. Vancouver improved to 6-3-7.
CHIVAS USA 1, IMPACT 0
CARSON, Calif. (AP) — Erick Torres scored on a sidewinding kick in the final minute of stoppage time to give Chivas USA the victory over Montreal.
Torres settled a deflected shot inside the penalty area and, with his back to the goal, sent a volley to the top right corner. It was Torres' 12th goal of the season, leaving him two goals behind New York's Bradley Wright-Phillips for the MLS lead.
The goal gave Chivas USA (5-7-5) its first three-game winning streak of the season — all shutouts.
The Impact (3-8-5) are the only team in the MLS without a road victory.