I also experienced that before on a 98 L300 Exceed gas. Bigla na lang mawawalaan ng power while driving. When it happened, we had to downshift and travel slowly. Turned out na barado ang fuel filter so kinakapos sa gas.
This happened about every 3-months and we had to change fuel filters regularly. We later found out that the real cause was madumi ang fuel tank - which quickly clogged the fuel filter. When we cleaned the fuel tank, the problem went away.