My gas gauge has been acting up lately.....after it gets past 3/4 tank it floats anytime while I'm driving......but here's the weird thing.....if I put it in neutral while waiting at a light or park it at night.....it starts working and showing the correct fuel level......I already bought a fuel level sender, just never have a chance to put it in cause of work.....What do you guys think it could be since it works correctly in those conditions......??