New Member Needs Help With A Toyota Qualis Its An Muv In India Its Got

[qualis]

i own a 2003 qualis im sure uve not heard of it but its similar to the kijang in indonesia.its a 2.4 d non turbo 75 bhp engine,the car has run 60.000kms and been serviced for every 5000 and for the past 10000kms ther seems to be loss in power drastically iv changed the filters and put kn air filters but compared to my other qualis its really underpowered i took it to the dealer but they tell me the is nothing wrong in the car but i can feel the diffrence it struggles to reach 120 kmh when the engine is cold its fine and when its run for 20 min its back to its old self . i think there is something wrong with the pump i really need ur help iv tried even autocar but they didnt reply please need ur help on this one :(