Eight cylinder vehicle running on only six cylinders

if it is missing as it should run on all eight. Either have a mechanic diagnose it or check compression and plug wires.

Is this a serious problem or can it be solved easily and cheap?

it depends what it is if it is an issue like a cylinder head gaskets or valves it is over $1500.00 to fix you really need to see what is the cause of it only running on six cylinders. It could be a lot and with the mileage posted i would say a bunch, but I have not seen it. See if the person will allow you to take it to a mechanic to check it over. it is well worth $50.00-$100.00 now than to be stuck with a large bill after you buy it. It could also be a bad engine which would require replacing or overhauling which can run quite high.

That was next question, i have 1992 Dodge Caravan it needs a head gaskets and cooling fans. Is it worth overhauling it if i supply the parts?

The labor Is most expensive on these type of repairs, so best to check around locally to find someone to do it with your parts.