With our bad fuel, all the heavy metals they put in it to increase the octane rating settles at the bottom of the tank. Also replace your fuel filter, its supposed to be replaced after 80000km. In other forums, people have also suggested to get the fuel tank cleaned, though I'm not sure whether this is safe or effective. But this is a problem you have to address quickly as this means your fuel pump is being stressed. An overstressed fuel pump is bound to fail sooner or later if the problem isn't taken care of.
Even my mechanic tells me to fill up as soon as as the fuel needle goes down to the last quarter. He has cases of several reborns with failed fuel pumps, and quoted a price of 45,000 for the pump. That was enough to scare me:)
