This one is my friends one this time. He was telling me that today when he was pushing his car above the 5000RPM mark the car wouldn't have the "umph" factor about it like before. He told me that it started just now and in the morning it was running fine. By the way he was going on petrol and wasn't running on CNG.
So the problem is that car wouldn't go flat out through the RPM range with the same velocity in the first 3 gears(he didn't check the rest of the gears). Any suggestions?? The car has done around 8k mileage.