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Discussion Starter #1
I started my truck yesterday and immediately the check engine light came on and it was idling very rough.

I took it to AutoZone to have the them read the codes and they thought it was probably the MAF sensor based on the codes they were getting.

I got an oil change this morning at Big-O-Tires and they checked the codes too. They said all 5 cylinders are misfiring and it would be best to have a full tune up done to check everything out. I asked about the MAF sensor and they said that it looks good and doesn't need to be cleaned our anything.

What do you guys think? Any suggestions at all? I've only had this truck since last fall and I honestly don't know if it has ever had a tune up.

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Posting the exact code numbers here goes a long way in reducing the amount of guessing.
 

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Just got beat up big time with the infamous P0171. many threads here for you to walk through. First off, find your vacuum leak most likely.
 

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Discussion Starter #9
Yeah I've been reading through other threads with P0171 and most of them say vacuum leak, but a few say O2 sensors or MAP sensors. Hopefully I can figure this out on my own because funds are a little tight right now.

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The MAP sensor is cheap and can be replaced in two minutes without tools.

At 95,000 you need to replace at least the front O2 sensor if funds are too tight to replace both the front and rear.
 

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I hear you on the funds ..... Checking for vacuum leak is tedious but cheap.
Throttle Body tight..... Brake Booster hose...... EGR system fresh air and Dirty Air line ...... Intake manifold...... MAF clean and tight
I had just installed a K&N intake. When I took it off, P0171 went away. With it on, I was able to get my instances of P0171 down a lot, BUT, never got rid of it completely until SuperMod did a tune on my I5. My O2 Sensors all tested good, even with 174K miles. Fuel pressure was well within specs. I had no evidence of misfires nor codes like the 30x some guys have gotten.
 
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