The CEL is probably the O2 sensor or something else. The rough running at 4000 RPM in neutral is probably the PCM saying "Stop That", IMHO laugh He said the stumble was happening weeks before the CEL. Thinking some more though, it could be the fuel cut-off caused the lean condition and threw the CEL then. Mine didn't do that. I agree he should have the codes checked. smile

"My Name is Richard. I am a Contouraholic."
1999 SE Sport Duratec ATX Spruce Green; Drop--In K&N Filter; VentShades;
Fog Lamp Fix Mod & PIAA510s with Bumper Braces & Stock Type aiming screw mod;
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