intermittent hiccups - pressure drop in fuel rail?
as suggested in other thread by Xulfiqar -
"in engine room, depressurize the fuel rail and test for flow first, if you get no flow then check the fuel filter, If you do have flow then test the fuel pressure in the rail, if its really low then your fuel pressure regulator maybe bad.
To test injector activity, get a 12V LED or a regular LED+resistor combo and stick it in the injector socket and crank the engine, you should see it blink, if its not blinking your ECU is not firing the injectors.
This means the distributor assembly is shot, there is a crank and cam sensor in the distributor. Usually its poor wiring connection (big multiplug on distributor)
you can also test the ignition spark - remove a plug wire, stick a screwdriver in it, lay it down on the valve cover so that there is a 1/4 inch gap between the shaft and some nut/bolt/stud - and crank the engine, it should show strong sparks. If you have no sparks but you had activity in the injectors and fuel rail pressure was correct then your ignition coil are culprit"