Guys

This one is driving me mad, and given some of the other obscure problems I have found on other vehicles, I cant believe that his one is currently beating me but it is, so I am looking foe some help to fix it so here goes!!

The car a lowish mileage 99 Nubira had been stood for about 18 months in our storage area, and we revived it and sold it to a group employee from another department about 3 months ago. Other than a few niggles, it has been fine, however as the weather has got colder, a problem has manifested itself, although I believe its been there all the time, but now becomming more pronounced as the ambient temperatures drop overnight.

Only occuring from stone cold, the engine starts pefectly, and ticks over as it should at about 1200 while stone cold. However when you come to drive the car, it has a really bad flat spot from rest and of course when you change gear. Changing from 1st say to second gear for example, you go to accelerate away on completion of the gear change and its as though someone for a split second has cut the fuel off, then the car picks up and accelerates as you would expect. This does this everytime you accelerate from low revs or having chaged gear, however as soon as the car has done 2 or 3 miles, the problem dissapears, and the car drives perfectly. The problem is of course, the car then has to be left for 6 or 7 hours to get cold enough for the problem to re occur, hence its driving me mad!! So far I have done a smoke test, and couldnt find any leaks, fitted 4 new plugs, checked all the plug leads, run it from cold with the vantage pro connected to monitor the secondary ht, checked the injection timing and throttle sensor voltages, checked all the vacuum pipes, checked the operation of the VGIS which is fine, and also checked the timing advance etc on the scanner. On checking the mixture when hot, it shows a lambda of 0.99 to 1.01, with between 35 and 120ppm of HC. On removing the plugs, 1 and 2 appear weak and the other 2 seem OK. The recorded pattern on the Vantage, showed one single firing of 18kv and a burn of 10kv which was higher than all the others, indicating to me that the car is running waek at that split second.

I am not really sure where to go from here, as we dont ususally get involved with Daewoo, as our mormal repair and diagnostic work is generally German and Swedish makes. However we sold him the car so we need to fix it, and I am therefore out of ideas at this point, so any help or suggestions from you guys would be most welcome.

Thanks in anticipation of your help Roger