has anyone experienced this thing where the first half of the tank of gas gets about 250 miles and the last half gets only about 150 miles and that is running until i am AT the bold empty mark not when the light comes on, so is this unusla or does this happen to anybody else

 

This is not unusual as most fuel gauges are not linear, i.e. the pointer at the the half mark does not mean the tank is exactly full.You will get more than150 miles if you drive till the engine stalls when tank is actually empty.