Pep reverted to a more defensive setup in the second half with the lead in hand, bringing on Nicolas Otamendi for Leroy Sane and resetting his fullbacks to standard positioning.
The move allowed City a foundation to bag the decisive third goal that all but sealed the title.
This season the 18-consecutive victories between August and December set a new Premier League record and the has spent a total of 240 days at the summit of the league since the start of the season.
However, United boss Jose Mourinho lambasted his players for basking in the glory of coming from 2-0 down to beat City 3-2 last weekend.
In the 24th minute City went 2-0 up as Gundogan converted from the penalty spot after Lloris fouled Sterling. They combined beautifully with Ilkay Gundogan, who deputised ably for Fernandinho in the defensive midfield role.
"We deserve top be punished, but the defeat was too heavy".
The attacking football City unfurled in the first half against United and the ferocious intensity they hit Liverpool with before the break in the quarter-final second leg bore comparison to any of their best work this season, as did the restorative 3-1 win at Tottenham. Jesus was shown a yellow card just in the stoppage time of the first half, the first 45 minute ended 2-1 in favour of Manchester City at the Wembley Stadium.
Third-from-bottom Southampton are five points from the safety zone after relegation rivals Crystal Palace beat Brighton & Hove Albion by the same score at Selhurst Park and Huddersfield Town beat Watford 1-0.
"As long as it is mathematically possible we will believe we can reach the top four", said Giroud.
All of Liverpool's prolific front three were on target as Sadio Mane and Roberto Firmino struck either side of Salah's deft header to take their combined tally for the season to 82.
Ian Rush and Roger Hunt were the others with Rush's single season record of 47 goals now well within reach for the prolific Egyptian.
City's 3-1 win means they can become champions against Swansea next week.
"We're nearly there", said Kevin de Bruyne, who was one of three City players nominated for PFA Player of the Year earlier on Saturday alongside David Silva and Leroy Sane.
Whether Wenger's 22-year reign in charge continues beyond this season now seems to hang on if Arsenal can get past a side that have reached two Champions League finals in the past four seasons.