so first port of call is.................
Clean the Maf Sensor
Possible plug change
Check the plugs.
It'll tell you a huge amount about whats going on in the cylinder. It'll give you a good indication why you are getting poor combustion.
Clean the throttle body.
It'll stop any hunting for idle, and is free.
Check for vac leaks, specfically on the PCV system hoses to the inlet manifold and the breather pipe.
Unplugging the MAF makes the engine fuel on a default map, as it doesn't know how much air it's getting.
If you don't start to misfire when you get up to temperature you know it's something that messing up the fuelling.
