Aguero famously scored an injury-time winner against Rangers to seal the 2011-12 Premier League title for City, but similar celebrations appear increasingly unlikely this time around as Manuel Pellegrini's team lie eight points behind leaders Chelsea after 11 games.
Charlie Austin had time to net two disallowed strikes before his sixth goal of the season gave QPR a 21st-minute lead, with City threatening to crumble under a ferocious early onslaught.
The visitors were indebted to a moment of brilliance from Aguero, who levelled the contest after 32 minutes, but a Martin Demichelis own goal meant a repeat of the scoreline City suffered at West Ham two weeks ago was on the cards.
However, Aguero left a prone Richard Dunne in his wake to level seven minutes from time and second-bottom QPR required a brave block by former City man Joey Barton from a Yaya Toure shot to preserve a deserved point.
Eliaquim Mangala replaced injured captain Vincent Kompany at the heart of the City defence, one of four changes to the XI that experienced contrasting fortunes against Manchester United and CSKA Moscow, while Bobby Zamora was preferred to Junior Hoilett for QPR.
A reshaped City backline featuring Bacary Sagna in place of Pablo Zabaleta soon looked vulnerable and Austin found the net twice in quick succession, only to have both efforts disallowed.
The striker headed home from a clearly offside position and, from the resulting free-kick, City goalkeeper Joe Hart hit the ball with his standing foot before mis-kicking to Austin.
Hart's failure to kick the ball directly out of his area meant a re-take was necessary, despite a fine finish from the former Burnley forward, but City were visibly unsettled and Hart was forced to deny Austin from close-range in the 15th minute before the same player finally got his goal.
Gael Clichy charged towards Mauricio Isla and lost his footing, enabling the Chile international to find Austin, who was played marginally onside by Mangala and slotted home.
A dreadful spell from City followed, littered with careless passing. Aguero appeared the only visiting player free of the malaise and there was quality and fortune on display when he hauled his misfiring side level.
Playing, like Austin, on the shoulder of the last man, Aguero wonderfully brought down Mangala's raking pass but the ball struck his hand as he controlled before beating Robert Green.
Nevertheless, QPR finished the half on top as Hart denied Austin once more following an error from Fernando.
Isla made a vital intervention to stop Aguero converting Jesus Navas' low cross from the right channel in the first minute of the second period, before Toure came agonisingly close to converting a move he launched down the opposite flank.
City belatedly found slightly more control in possession but a last-ditch interception was required from Fernando in the 62nd minute, with Zamora poised to restore QPR's lead.
Edin Dzeko departed with an injury only four minutes after coming on as a substitute and City's misery appeared complete when Demichelis put Austin's cross into his own net under pressure from Zamora in the 76th minute, after Fernando had ceded possession to Fernando Vargas.
Again Aguero led a lone charge for the visitors, rounding Green only to see Dunne clear his shot from the goalmouth.
Dunne's centre-back partner Steven Caulker then nodded a header from replacement James Milner off the line and Green denied Toure in the 80th minute before Aguero got the second goal that his efforts, if not those of his team-mates, deserved.
