1994 Civic Bali 1.4 UK

Just got this car from my cousin, he has replaced all ignition items plugs, cap, leads, rotor. Also replaced fuel filter and had dissy remanufactured.
Car is running OK but is a little bit hesitant and has flat spots when accelerating, fuel economy though is excellent, basically are there any common issues I might also check My cousin did adjust the timing as far as he could which made the car run a dream but every now and again he thought the engine went into safe mode and stopped.

Thanks.