Our sentra had a similar problem:
- Namamatay bigla while cruising
- Minsan walang fuel na pumapasok while stepping on accelerator
- Mahirap i-start, pag namatayan

We did the following:
1. Changed the fuel filter - ganun pa din
2. Inspected/checked spark plugs - wala naman dun problema
3. Brought to a high-end car shop for electronics testing - found that the problem
was the distributor, mahina yung pumapasok na koryente sa system

Pinalitan yung distributor about 1.5K petot yata yun (surplus). Then yun, ayus na.