I had the same problems. The fuel quantity thingy was failing in the FIP. If I came off cruise I used to see a momentary yellow engine light on the dash.
The only way to cure the smoke was to use manual override on the auto gearbox as high revs stopped the smoking. I got a replacement engine in the end, it was cheaper than getting the FIP reburbished.
I removed the turbo and had it checked. I replaced all the turbo pipes - they were fine. MAF sensor was reading out of range. Engine intake temps were stupid (I can't remember exactly but it was like -300C). I had the FIP o rings and seals all replaced. Nothing made any difference. Which is why I went for a full replacement engine. All been fine since :-D
