1992 lesabre

It just started doing this seviouly. After about fourty miles it started bucking and barely going. I let it sit for a couple of hours and had about ten miles to get home started doing it again after about five miles. Also used twice the amount of gas. Is this a fuel filter?

The Oxygen Sensor would cause the bad mileage. I used like 9 gallons in 20 miles before. It tells the ECM how to control the gas and air mixture to the fuel injectors. This could also cause hesistations on stop and go. The O2 is normally on the back exhaust pipe coming from behind the engine.

i doubt that it could be the 02 sensor because if they are faulty the computer will sense that and run them in open loop all the time taking readings from all the other sensors like the coolant temp, air temp etc etc

the car is designed to go into closed loop when the 02 sensor gets hot enough (over 600 degrees) to start reading accurately and at that point if it is working the car will go into closed loop and the mixture will be adjusted pretty much from the readings from the 02 sensor alone

if you dont have a working 02 it will never go into closed loop and if that happens it will trip the service engine soon light and you wont have as much power and your gas milage will suffer a little bit but it wont cause you to use 9 gallons of gas in 20 miles and it wont cause your car to buck and miss or run that poorly in general

i would take a look at your plug wires, spark plugs, and the coil packs was it damp out that day? if it was then i would definitely think it could be the any one of them

my car did something very similar it would start bucking and missing under power and when you would let it sit for a bit it would get better it ended being a faulty coil on my coil pack