Had this exact problem This is how I solved it
steps 1 & 2 will cure 80% of the time, and are VERY EASY TO DO
1) Remove idle control valve (2 screws & unclip block connector =3D 2 min job) use whit= e spirit and a paint brush to clean of crap from the sensor, it may look clean enough but= this WILL make a difference to any unexplained self revving cycles particularly on c= old morning starts.2) Disassemble throttle body and clean that out with white spirit and a 1 inch paint br= ush (cut bristles to about 2 inches)
3) Still running rough? Put in an new oxygen sensor - just lob one in - they are only good= for 40k miles so get an after market NGK DO NOT USE A UNIVERSAL SENSOR they have a heater= built in and theyt are all different wattages etc so they will cause PROBLEMS - I HAVE H= AD THESE PROBLEMS SO I KNOW FIRST HAND get the exact one for the engine in question. =3a) do this ONLY if you find medium to heavyish deposits in item 3 - remove the carburet= ion feed rail (next item on from the throttle body)
4) only if idle and engine run LUMPY =3D you may have a blocked or faulty injector so to c= ure it 4a) run some injector cleaner though (any car store) 4b) (if you are technicall= y able) get an injector recon kit from ebay and do em all for about =C2=A340 OR buy a set o= f new injectors for over =C2=A3300 (your choice!)5) finally if you still have problems the its the HT leads or VERY unlikely its the ECU,= but there is normally a yellow light on if the ECU had a problem with one of its sensors.= If you have this issue then get a ODBC2 reader from ebay for =C2=A330 and read in the err= or code - this will pinpoint any remaining issues.
best regards & good luck
url:
formatting link