Gosh...i have been having the same problem for the last 3 months or so. It actually started after the miggy consumed some dodgy fuel. I had the tank cleaned and petrol filter replaced. But it did not make any difference.
I listened to advice here and changed MAF sensor ..again no difference.
I changed the CRANK SENSOR with a brand new GM one again no difference.
I have also changed the CAM SENSOR with a brand new GM one....still did not make a difference.
I took to the local dealers here with TECH II......no fault codes. The car was there for 5 days and they fiddled with everything including injector nozzles, still no joy.
I replaced the engine temprature sensor and switch 2 days ago still no joy.
I now have a mechanic who is suggesting i get IRIDIUM spark plus becuase the ones i have do not seem to spark properly!! I have ordered them from ebay an will advice once fitted.
Oh did i mention that i also changed the coil back and fitted a brand new bosch one?

?
At least on the brighter side my car only plays up in the morning for about 30 seconds and you have to turn the key a few times. After it warms up it runs perfect the whole day!!!!
It would be great if we could find a solution to this problem affecting the 2.2's
From my experience with these problem i would suggested you go about changing parts especially if you have to buy them. Luckily for me as i am at the other end of the world i had stocked up on the parts that are mostly likely to fail (Cam,crank,maf,coil pack etc)