Toyota Repair: 1993 Previa seems to be starved for fuel, water contamination, full tank

Question
My 1993 2WD Previa with 180,000 miles on it begins to hesitate severely when the gas level drops to about 2/3 to 1/2 of a tank (seems to be a bit temperature dependent - in colder temps I need to fill the tank earlier).The van was stored for about 18 months before being brought back onto the road.  She was started periodically, but always had low levels of gas in the tank.The car runs fine with a full tank of gas. Only has difficulty starting if fuel is at half a tank or so.  It needs new plugs, but I don't think that that is the issue.  Could a clogged fuel filter be at fault? The car was rear-ended before I bought it last year, but only visible damage was to the bumper. I would appreciate your thoughts about the problem and what I should do or have done. Thanks, Ken


Answer
re you sure the fuel tank is not dented or shows any signs of damage from the accident?
The only other thing I would recommend doing is to drain out all the gas that is in the fuel tank when this problem starts and then fill it with fresh fuel, it is possible that when it was stored the fuel became contaminated and won't mix with the fresh fuel, I thought about water contamination but since water is heavier than gasoline the problem would be there all the time, good luck with this.