2000 Focus hesitation on accel, studder in idle/cruise

Sitting at idle it'll studder every 30sec or so, stomp the gas and it hesitates then revs fine. Driving at 45-50 or so and barely touch the gas and it stumbles then takes off.

Tried injector cleaner, air filter, Same.

Tried plug wires, Same, tried plugs, cleared up completly for one drive, next day same thing, getting worse.

Took it to the ford place, said #4 missing, said bad wires, (just replaced them) changed them anyway, still the same.

One thing i've notice is that there is a arcing/ticking sound when the engine studders comming from the left side of the dash, tach?

Im thinking cracked #4 coil post arcing into the dash thru the tach wires. What do ya'll think?

Thanks