Rough idle, flashing CEL, p0301 code

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So I’ve tried to run through all the previous post to see if anything was similar and I found a few and checked the things mentioned on those but none seem to be my issue. So I have a rough idle with a flashing CEL, the first thing I checked was the IAC… put a new one on and no change. So I took that back and bought a MAF sensor (I cleaned my original first no change but just wanted to rule it out) and it cleared up the rough idle….for 2 days! Now it’s doing it again. Anyone have any idea why that would fix it temporarily? Did the new one go bad or is something contaminating it that quick. I have plugs and wires on order (it’s time @186k) and new elbow for the vacuum lines near the intake. Just wanted to throw this question out there in case anyone has any ideas! Thanks
 

oknopa

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So I’ve tried to run through all the previous post to see if anything was similar and I found a few and checked the things mentioned on those but none seem to be my issue. So I have a rough idle with a flashing CEL, the first thing I checked was the IAC… put a new one on and no change. So I took that back and bought a MAF sensor (I cleaned my original first no change but just wanted to rule it out) and it cleared up the rough idle….for 2 days! Now it’s doing it again. Anyone have any idea why that would fix it temporarily? Did the new one go bad or is something contaminating it that quick. I have plugs and wires on order (it’s time @186k) and new elbow for the vacuum lines near the intake. Just wanted to throw this question out there in case anyone has any ideas! Thanks
 
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I had an intermittant rough idle after the engine was warm. IAC and PCV checked good. Ended up being some very apparent carbon buildup at the end of the EGR input tube in the throttle body. (I needed a dentist's mirror to get in there and see it.) I cleared out the carbon (chunks of it) and replaced the EGR for good measure. Been running nice and smooth ever since (month or two). Good luck!
 

DILLARD000

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So I’ve tried to run through all the previous post to see if anything was similar and I found a few and checked the things mentioned on those but none seem to be my issue. So I have a rough idle with a flashing CEL, the first thing I checked was the IAC… put a new one on and no change. So I took that back and bought a MAF sensor (I cleaned my original first no change but just wanted to rule it out) and it cleared up the rough idle….for 2 days! Now it’s doing it again. Anyone have any idea why that would fix it temporarily? Did the new one go bad or is something contaminating it that quick. I have plugs and wires on order (it’s time @186k) and new elbow for the vacuum lines near the intake. Just wanted to throw this question out there in case anyone has any ideas! Thanks
OBD2 TroubleCode p0301 = Cylinder1 MisFire
Noting your specs Year+Model+Engin+Trans+TCase+Diffs+... in your Threads+Signature+Profile
will encourage\expedite getting responses.
Per your Profile, you've got a 2001 [email protected];
if still running original Plugs+Wires+OxSensors+PCVValve+... it's 86kMiles overdue;
get those replaced first, then see what you've got.
 
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UPDATE: I took the truck to my local mechanic as opposed to wasting time and money trying to throw parts at it, it ended up being a failed fuel injector for cyl 1 and the connector was also broke. cost about 200 bucks but i had a crap ton of other work done while i was at it including a tune up and replacing the leaky valve cover gaskets. It runs great now :) appreciate the replies though
 
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