Liam Armstrong and Josh McKenzie both saw red within two minutes of each other in the second half following the former’s dismissal on 56 minutes.
Connor Bartle created the opener for Rob Morgan fired on 13 minutes with Jonathan Margetts doubling the lead in the 77th minute.
Khalsa defender Andrew Parsons reduced the deficit shortly after but Bartle was involved again to set up Marshall Willock who wrapped up the points with a third for Stamford four minutes from time.
The defeat leaves Sporting in fifth place in the last of the play-off places with rivals Coleshill and Corby both a point behind but each with a game in hand.
Sporting entertain Corby next week in a promotion play-off six pointer.