Carlos Munoz, Ryan Briscoe and Scott Dixon completed the top five.
Montoya, who won from the pole, took the lead for good when Tony Kanaan was forced to pit for fuel with four laps left. Montoya took it from there and continued to stamp himself a player in the championship hunt.
Montoya damaged his front wing when he connected with Power on a pass for the lead on the 167th lap. Power's penalty troubles continued at Pocono when he blocked Castroneves on the 171st lap, effectively ending his shot at victory.
Jack Hawksworth missed the race because of a heart contusion.
Hawksworth was injured Saturday in an accident during the second practice session.
He was evaluated and released from the infield care center. Hawksworth stayed overnight for observation at a hospital and was released Sunday.
• Lewis Hamilton won a dramatic crash-hit British Grand Prix on Sunday in Silverstone, England, to cut Mercedes team-mate Nico Rosberg's lead in the drivers' championship from 29 points to four after the German had his first non-finish of the season.
Hamilton, the 2008 champion, started sixth on the grid. The British driver leapt to fourth on the opening lap before it was red-flagged, and suspended for an hour, following a crash involving 2007 champion Kimi Raikkonen of Ferrari and Felipe Massa of Williams.
Hamilton then took the lead after 29 laps as Rosberg retired with gearbox failure.
• John Force raced to his 140th career victory Sunday, beating Ron Capps in the Funny Car final in the Summit Racing Equipment NHRA Nationals in Norwalk, Ohio.
The 65-year-old Force powered his Ford Mustang to a winning pass of 4.113 seconds at 317.27 mph for his first victory in Norwalk. He also won the season-opening event in Pomona, California.
Second in the points standings, Force won his record 16th season title last year.
Antron Brown won in Top Fuel, Erica Enders-Stevens in Pro Stock, and Andrew Hines in Pro Stock.
Final 3 bids for 2022 to be decided
Olympics • Olympic leaders meet Monday to decide which cities make the cut in the race for the 2022 Winter Olympics. It should be an easy choice.
After a series of voter rejections and city withdrawals, only three contenders are left standing and the future of one remains uncertain.
The International Olympic Committee executive board is expected to keep all three remaining candidates: Almaty, Kazakhstan; Beijing; and Oslo.
Also on the agenda for the three-day meeting in Lausanne, Switzerland, is an update on Rio de Janeiro's delayed preparations for the 2016 Olympics, possible venue changes for the 2020 Tokyo Games and a review of IOC President Thomas Bach's plans for the future of the Olympic movement.
From wire reports