Joshua Lyons

I have an 05 F150 with that wonderful 5.4L with 168,000 miles on it. I'm religious when it comes to oil changes and most maintenance on it. I just bought my wife for Christmas an 05 expedition with the same 5.4L with 170,000 miles. We got a week out of it before the engine needed to be replaced due to oil not getting to the back of the banks and the bearings were burnt up. So now I'm very nervous about mine. Right after her car went down the truck started to act funny. I changed the oil to a lighter weight 5w20 vice my typical 10w30 to ensure oil flow. The truck then ran at a lower rpm at idle, 500 and stalled a few times. I changed the gas filter and it was in very bad shape (so was my face after ingesting some low octane) and that brought the rpm slightly and no more stalling. But still a lack of power. Cleaned a bunch of buildup in the throttle body and installed a new MAF sensor and RPMs are fine about 550 at idle but still a lack of power. My OBD says that it's only running 100hp max. Am I smoking crack and just gun shy because of the wife's car or where can I look from here. Keep in mind I am no master mechanic and already took a huge hit replacing the wife's motor so I can't spend a lot of $$$

grss429

have plugs/coils been done?

Joshua Lyons

Yes within the last 10,000 miles

Joshua Lyons

I doubt the plugs would go bad so quickly but is it possible the coils could have failed? The are msd aftermarket ones

techrep

iTrader: (1)

so...were the plugs changed prior to 158K ?