Hi, I was driving back home in my 1.4 Linea petrol , from chandigarh to delhi. I stoped at a HP petrol pump near Haveli at Ambala on the road. My tank was half empty...but after fillin 7 litres the petrol guy said tank is full. I laughed at him and resumed my journey. After few kms the silencer starting jerking and knocking like the exhaust gas is not coming out. while car was stalled car vibrated heavily...then while picking on first gear it jerked and made noise of an autorikshaw...i thought the silencer is broken but drove car for 180 kms to delhi. Suddenly after reaching delhi the vibration in the car started fading. Now car when stalled is not vibrating...but there is small shuderring/vibration when picking on gear 1 and performance is low of gear 2. I think the problem occured because of adultered petrol...or can it be some other issue??? What should be my next step?? I dont want to goto tass unnecesarily since they would take out fault in everything starting from fuel injector spark plugs to silencer.... Please suggest.