Hi Every1

I am new here, I have a 2001 golf 1.4 16v that is misfiring in cylinders 1 & 2 according to a trouble code computer. Strangely enough when the car is started cold and driven continously it is absolutely fine, but if left to idle around 8 mins or so, the engine loses idle and the engine goes to limp mode.....hence the misfiring starts....if you turn off the engine and start it again its fine...then afte a few mins or so goes back to limp mode and stays that way...could it be the cylinder valves? so far i have changed:

coil pack, plugs

Any ideas?