You are stumbling around changing parts with no real idea of what the
problem is. You still have the chance to save yourself some money.
Just take the car to a mechanic with the proper diagnostic equipment
and let them find the cause of the problem and fix it.

> Sharshera wrote:
> I have a 1988 Volvo 740 GLE Wagon. It runs very rich. It does something
> like 18mpg or so in the city and around 23mpg or so on the highway.
>
> I changed the O2 sensor, the spark plugs are relatively new, the gas
> pressure regulator, the fuel filter. I have tried additives to clean
> injector but all this just went in vein.
>
> Does anyone have any clues as what to investigate? What might be the
> problem?
> I like the car very much and hope that I can drive more often but I
> only try to take it in longer trips because of its bad fuel economy.
>
> The car has 150Kmiles on it.
>
>
> Any help will be very much appreciated.