Is the engine tempurature gauge reaching the red zone? If it is, then the first thing you should do is check the coolant level, if that is ok, then check the thermostat. If that is ok, then the water pump. But if it heats up really fast, it is probably very low on coolant.
However, if you have some kind of opening or leak in the firewall (seperates engine from interior of cab area ) then some of the heat might work its way towards your feet, which would be very close to the firewall....
goodluck
