My truck began 'stumbling' when the engine is not quite to operating temperature. I call it 'stumbling' since it feels more like running an engine with incorrect A/F ratio rather than a misfire. But when heated up it's much better but still has an occasional problem that now feels like a misfire! It actually does better with the A/C on.

No codes or check engine light.

I only have about 128K miles on the truck and the plugs were replace at about 85K when a plug coil went bad.

Before I spend a bunch of money letting Ford randomly replace stuff... does anyone have an idea what the real problem might be?

Thanks for your words of wisdom.

 

Probably another cop, if good plugs were used.

 

Not aware of a convenient and knowledgeable Ford mechanic in the Duluth, GA area other than the dealership. So here I go for the high dollar fix. They found 2 COP's that were 'weak', No. 3 and No. 5 cylinders. After replacing the COP's, two plugs, decarbonizing and $623 she runs like new again!

Not bad when I think about it.... a 15 yr old truck I've only spent about $1200 dollars on in what I consider abnormal repairs. 3 COP's, a fuel pump, and a passenger side door lock.