First 2 things to check asap in my opinion are the earth at the back of the cylinder head for the coilpack loom - It can fray and break here so causes a weak spark = bad firing, wet plugs.
Also, unplug the Engine Temp Sensor - The 2 wire plug just before the thermostat housing - Unplug this, and then start the car and see if it improves, it's a quick easy thing to check. If it improves, then test the resistance of the sensor to see if it's within range and you may find it's knackered.
Hope this helps.