1999 Ford F-150 Running Rough at Idle

  • 1999 FORD F-150

Engine Performance problem
1999 Ford F150 V8 Four Wheel Drive Automatic 150000 miles

I have a 1999 f150 lariat with a 5.4L. It recently started running rough at idle so I replaced the pcv valve and fuel filter. After replacing these it still ran rough. I took it up to advanced auto and and had them do a check engine light read and it said 3 of the 4 o2 sensors were bad. I replaced all 4 o2 sensors and it ran fine for about a day and the check engine light came back on. I again took it up to advanced and had them hook it up and now its saying its running lean. I am alittle stumped and to short on cash to take it to a shop. I had thought maybe mass flow air sensor but I am not really sure. I would greatly appreciate any help.

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Wednesday, May 26th, 2010 AT 10:23 PM

1 Reply


Could be EGR valve leaking, dirty injectors, MAF sensor/oxygen sensor, vacuum leaks and low fuel pressure

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Wednesday, May 26th, 2010 AT 11:56 PM

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