Hi there, i have a 2002 1.6 ford focus with 51k on clock. it has recently developed a running issue,

sometimes (getting more and more offten) there is a faint popping sound comming from the engine, this causes a loss of power/revs and hesitation when pulling off. sometimes it even stalls

power seems normal at higher rev's

so far we have done a service including sparks and fuel filter.

what else do you think i should be looking at, i was thinking coil pack and leads. but if you guys think it could be somthing else i change that instead.