Why do I have a small miss at idle and less than average fuel economy? on 2002 Ford Explorer Sport Trac

I have a 2002 Ford Explorer Sport Trac that runs well but it has a small, noticeable miss at idle. Acceleration and power are good but gas mileage is down a bit. It has also stalled a couple times while warm backing up (idle seems to be very low when backing up). It has 83,000 and we are the second owners. I have service records but don't see a tune up, plug change, etc. in the file. I think I read these need plugs changed at 60,000? There are no codes currently. The last thing done was a new throttle position sensor right before we bought it. I'm guessing a plug/wire set change? Or is there a way to set the TPS and maybe it was done wrong? air filter is new. I'm getting 12-13 mpg. city with a V-6 driven very easy and soft.

by in Whittier, CA on December 21, 2013
2 answers 2 comments
ANSWER by on December 21, 2013
The common problem with these symptoms is the intake manifold 'o' rings fail causing a vacuum leak.
COMMENT by on December 21, 2013
Thank you for your response. Wouldn't this cause a code or check engine light to come on for a lean run condition? So far no light on or codes.
COMMENT by on December 21, 2013
It should but, so should something else. At idle miss is normally a vacuum leak. Get spray bottle and spray a fair amount around the intake while running and listen for a change of idle speed.
ANSWER by on December 23, 2013
Sometimes we have seen the Idle Air Control Valves get plugged up and not cause a light to come on. When they get plugged it can make the idle very irratic and vehicle may even stall when coming to a stop. This has been a common problem for us here in Southern California for a few years....it might be the climate or the fuel but it is common. We would be more than happy to inspect the vehicle for you at no cost and let you know what the costs would be. There are many things that can cause the symptoms that you are having and unfortunately the only way to know exactly what is wrong is to inspect the vehicle. I hope this helps!!!! Have A Very Merry Christmas!!! Steve Your Car Specialists 13903 Marquardt Ave Santa Fe Springs, CA 90670 562-802-1332 www.YourCarSpecialists.com

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