Urgent please help me !

[betina]

Hi,
I've got a Holden Commodore VT V6 wagon 1998.
When the weather is too hot or I drive during long time it get a problem.
Once the problem appears when I press the acceleration pedal it gives jolts as if there was no gas and sometimes even hold it. Then I have to wait one to two minutes to restart.
I have to constantly roll with the hood open for longer it rolls smoothly but sometimes nothing helps! I already changed the fuel filter, oil filter and radiator.
I wonder if the problem does not come from the thermostat or the fuel pump but I think actually being there has to do with heat.
What do you think ?

Thanks a lot