Fuel Mixture

My 87 Turbo has a very heavy carbon build up on the spark plugs, which I beleive is an indication that the fuel mixture is wrong. Is this something that I can adjust myself or best left to a professional? If it is a DIY job what do I need to adjust and where do I find it? Could the carbon on the spark plugs be an indication of anything else? It is very unresponsive and lumpy on cold start up.

Perhaps a sensor, or the wiring to it. Lumpy when cold sounds like it thinks it is warm, again perhaps a sensor. Hire DGs diagnostic unit, it will check all your sensors as the ECU sees them, and cheaper than any trip to a Stealer.