this thread reminded of my trip to Noshehra/Topi/Tarbela with friends on my Recon Corolla 86 back in 90's.
Soon after the Lahore petrol tank finished and refuelled car lost the pick and had knocking issues, we ended up changing plugs, oil change etc on the way but no avail and my friend accusing on failing to service the car properly. we learnt to live with underpowered car for few days and accepted its the car!
on the way back, we refuelled at Chenab bridge petrol station.... and corolla rocked back to its long lost power!!! it was bad fuel all along and unfortunately we bumped to all the bad ones on the way!!!
so I guess its all about management of the very station not the brand, many mix water, kerosene or anthing else they feel suitable.