If you say the car is 'missing' - i.e. jolts and has sudden on/off power characteristics, that would indicate an ignition related problem.
A fuel flow problem would be somewhat less sudden, and feel softer.
If you like, you can often say an electrics/ignition problem would feel electric, a liquid problem would feel liquid.....
So, particularly if you have missing and do not know the plug wires on the car - replace them.
First port of call for a misfire usually, even if they seem fine.
A '98 VW Polo I am currently using had misfiring which couldn't be cured for ages. Turns out someone installed cheapo 'universal' plug wires, which would short out to the radio shield around the distributor, even though the wires were quite new.
Remember, fit original parts!!
2.5-16v 1990 90,000m Astral Silver
2.0E 8v 1986 107,000m Black