Hi all, the issue im having is my c20let engine starts and runs fine when cold, every time i take it out and the engine starts to get warm the engine starts to hold back and splutter a bit then stall once stopped, the spark plugs are really sooty black, now it has not logged any fault codes in the ecu, things ive done so far, change the ecu, changed MAF sensor, CTS, ISCV, TPS, check all voltages to the sensors, checked all the earths, nothing, the only things i havent changed are the ignition coil lead/HT leads/ plugs/dizy, would a coil lead start to break down once it gets warm and cause this, weak spark hense sooty plugs? dont know desperately seeking help, when cold, its crazy to drive but not long before the fault appears, but disapears when cold, then re appears when warm again, any help please