Q: Car still runs bad. Replaced fuel and oil filter. Also replaced knock sensor and got an oil change. Car stalls and has slow speed.

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I was getting the P0172 and P0171 codes when I got a diagnostic. I got the sparkplugs changed and it ran a little better. I got the fuel filter changed and the oil filter changed and it ran a little better. Then I got the knock sensor changed and it ran a little better. It still stalls and runs slow. It is also slow to accelerate. What else can be the problem? Could you provide a list of possible fixes to this problem?

My car has 204000 miles.
My car has an automatic transmission.

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Hi there. The P0171 OBD-II trouble code means that, on the first bank of the engine, the fuel system is running weak or a vacuum leak exists near this side of the engine. A lean condition occurs when the engine either receives too little fuel or too much air. The P0172 code is set when the ECU senses that there may be too much gasoline present in the air-fuel mixture of the engine. It would be a good idea to click those two blue links to read the articles on those codes, describe the possible sources and recommend solutions. However, it would be more cost effective to have a professional mobile mechanic come to your location and complete a car is slow to accelerate inspection, so they can isolate the issues and recommend the right repairs.

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