Check plug leads are secure at both ends.
Check the spark plugs for condition - gap & fouling
When checking the plugs, also check the tails of the plugs if they are screw on, if these are loose it can casue misfire.

When the fuel filter becomes blocked the car generally feels flat & doughy,
It's generally a progressive thing rather than a sudden misfire situaton.
Leads comming loose off the dissy cap or plugs is more likley...
Or water down the spark plug holes from washing the engine.