how do I get it to idle smooth and pass smog?

1990 FORD F-150
180 MILES
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FREAKYTOASTER777
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4.9l 5speed 4X4 duel tanks did tune up and replaced fuel pressure regulator.Still is idleing too rich and has a missfire at idle.
May 5, 2012 at 8:47 PM
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ASEMASTER6371
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look for vacuum leaks. is the check engine light on?? o2 sensors were common back in the day. map sensors were issues as well. all need to be verified by a shop with a scan tool.

Roy
May 5, 2012 at 8:49 PM
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FREAKYTOASTER777
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check engine light is on steady, i checked seld diagnostic and codes "31" and "67" are flashed Would the evp voltage being low (code 31) make it do that?
May 5, 2012 at 8:55 PM
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ASEMASTER6371
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not really unless it is pulling raw fuel from the tank but not likely. you need some help here unless you have a scan tool

Roy
May 5, 2012 at 8:58 PM
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FREAKYTOASTER777
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Ok, thanks for your help
May 5, 2012 at 9:03 PM
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ASEMASTER6371
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good luck
May 5, 2012 at 9:06 PM
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