525i 1992 power surge

[Tony]

My 1992 525i manual has a power surge when climbing hills or under acceleration. It is especially bad after the car has been driven, parked for 10 minutes then re started. It starts fine and idles smoothly, however as you accelerate into 2nd and 3rd gears, there is a temporary TOTAL loss of power which suddenly returns to power. This could obviously be dangerous. When the power is surging, the economy gauge swings back and forth toward the lower consumption readings. It seems to give a lower reading in time with the drop in power.

Also, when the car is cruising (60km/h) on light throttle settings immediately after the car is started when cold, it stutters along for the first 2 km or so, then suddenly flicks over to run smoothly and with more power. It is like a switch has been turned on. It feels similar to when you are driving an old car with choke that is pulled fully out then suddenly pushed in.

I have had the O2 sensor replaced and this has not changed the problem. The car has had a recent Inspection II service and had a dyno test which showed that it was running slightly lean, however no one can identify the problem.

I would be very grateful for any suggestions or info from people who have encountered similar problems. please reply to my e-mail: antgumley@hotmail.com. Thanks