[asanga]

do few simple inexpensive things first and work your way up.

ignition check is a good start, specially if its hesitates under load.

check leads for any cracks and in the dark you can see if they are leaking sparks (arcs).

Check the dissy cap (specially the spring loaded nipple in the middle) and rotor also.

Replace fuel & air filters

Run a bottle of injector cleaner with full tank of petrol.

Base idle & timing is set by putting ECU into diagnostic mode (connecting TEN to GND in data link connector in engine bay near fuse & realy box). If you have a timing light you can do this quite easily. once you remove the jumper wire between TEN & GND the ECU takes over and alters the timing.

Its a good thing to do a error code check as well (in case if you have a faulty sensor).
You can do this with a LED and count the short & long pluses to extract any error codes.

O2 sensor can be checked with a voltmeter, it should fluctuate between 0.2V and 0.8V when the engine is fully warmed up & idling. This may also indicate you if your injectors or fuel delivery system is bad if the engine is running lean all times.