Cadillac Repair: 1979 Cadillac Seville, 1979 cadillac seville, cadillac seville

Question
On that 350 olds Fuel Injected engine, is there a possibility of better mileage. I'm getting 11 mpg on the highway, and about 4 in the city.  Burning rich so they tell me. Only 54000 miles and never any major operations to it. Fuel injectors have been cleaned and all the reg maintenance done.

Answer
Test the COOLANT SENSOR with an OHM METER when it is COLD and when it is HOT to make sure it is within calibration specs.

Check the vacuum hose from the ECU computer under the dash to where it attaches to the intake manifold for being extremly soft and or has small cracks in it. If it were mine I would replace it.

CAUTION: NEVER EVER start the engine with this ECU vacuum line disconnected from either the ECU or manifold vacuum or you will DESTROY the ECU computer.