99 Winstar, Miss at low speed

Vehicle has 105,000 miles, Had service eng light for some time now, Codes showed bank one and bank two lean, Had the fuel filters replaced, same problem. Had the spark plugs replaced,( they really did need changing) . The
service eng light came on the first time I drove it ten miles.It appears to miss or run rough at a slow speed (20 to 30 mph, does not happen all the time. When it does, I can increase the accelerator slightly and it smoothes out. Any ideas on this one,( I have not had the codes checked since replacing the plugs) Thanks Charlie snipped-for-privacy@bellsouth.net
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could be one of the most common 99 and 00 windstar problems, http://www.leckemby.net/windstar/windstar01.html i think I spent about $100 for the parts, only thing I could not get online or at a parts store was the valve cover, got the rest at www.rockauto.com

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Thanks for the info guys, Sounds like thats my problem, May be a little over my head at this stage of my life,(67 yrs old and no place to work on it) But I can now look at the trouble spots for anything loose or disconnected, The pictures were great, I will post the fix when its done Charlie

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I have same problem on my 99 Windstar. Codes 171 & 174. No other clues. Today I just happened to find that one of the control rods on the IMRC ( Intake Manifold Runner Control ) was off and just sitting there. This sits on the left side of the intake manifold (plenum) and in my model is one control unit with two control rods (arms) going forward and rearward to control the "butterfly valves". Haven't yet got to it but you might check yours. It might be the cause of the codes.
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