Thanks for the instant reply :)
Just 4 months ago, the intercooler and turbo was serviced as the car was failing the pollution test! After cleaning both, it was just 0.2 under the max pollution level.. :(
Intercooler and turbo werr absolutely fine. There was a small leak in intercooler which used to make hissing sound on acceleration (still it is hissing lil bit), but as per the service station guy, he told that it's alright nothing to worry about.
Now I'm planning to change the MAF sensor. Found it faulty.. (How much did it cost?)
This problem started when my battery went dead. Many times i started the car in-gear. This could probably the main reason for what-all is happening :(