Strange misfire on cold engine

[LukeZS96]

Lads having serious problems with my ZS. For the first 5/10 minutes of driving when I let off the throttle the car misfires and splutters like mad. It hesitates really bad under harsh acceleration. This goes away after about 5/10 minutes and then the car drives fine, no loss of power and no misfires at all. Another thing for the first 5/10 minutes the idle is around 1100 RPM even at normal operating temp. It used to settle to around 850 after 5 minutes until this problem came up. Its a 2005 ZS 120 1.8. Have recently changed plugs, HT leads and coil packs along with a fresh fuel and air filter. No fault codes what so ever and no EML. Swapped crank, cam, throttle position and MAP sensors for known good ones and still no joy. Any ideas on where to go next?