Have a city idsi vario 2005 clocked 110,000 km. Car starts fine on cold and hot but if put in D with AC on and brake pressed then rpm drop to around 500 and engine shudders like it is going to stall. Vibration is so intense it shakes the car's body. But once it starts moving the vibration is gone.
But pick is not very good
Also mileage is very poor 8 to 9 km / liter max with ac in lahore city driving
Work done so far
-Throttle body service plus IACV valve cleaned.
- Intake manifold washed after removing
- pcv valve cleaned and hoses replaced.pcv hose was collapsed from connecting point to intake manifold
- Injector cleaning done from magic motors
-tappets adjusted from honda
- all 8 spark plugs changed
-Fuel filter cleaned
But the vibration in D with AC and poor mileage are still there. What else could be the cause?