Cadillac Repair: i990 cadillac sedan deville problems, cadillac sedan deville, fuel mileage

Question
car runs terrible but when i bought the car a month ago it was perfectly fine. i think it would be easier to give symptoms.  symptoms are:  low horspower, vibration at low rpm even at highway speed, takes about a half hour to reach highway speed(feels like car is only running on 4 or less cylinders), poor fuel mileage, water from ehaust but water level in radiator remains constant, on hihgway when i try pick up speed by pushing pedal down it down shifts hard and still is unable to accelerate.alot i know

Answer
If it were me i would check the fuses for 22 and 23, which are the fuel rails, make sure none of them are blown, if its not blown, check the throttle body for carbon build up. Then try to at least change the spark plugs, and let the cylinders dry out for 15-20 minutes. If your willing,  replace the distributor cap and rotor, and ignition cables.