My 2001 f-150 lariat FX4 when hitting the accelerator the truck seems to bog or go in and out of having power. I’ve been trying to solve this problem for awhile now by replacing the fuel filter, spark plugs, coils and air filter. None of these have affected the loss of power it remains the same. Any ideas would be appreciated.

 

Can you provide an RPM and vehicle speed range that this occurs in? How long does it occur? Best if you know what gear you're in when it happens. Would be nice if you could get some codes.

Clearing the keep alive memory (KAM) by unplugging the battery for a minute, unplugging the maf then starting it and going for a ride can eliminate the maf as a possible cause.

 

does it happen in OD between about 1100-1400 RPM?

 

only happens in 1-2 gear and only at 1100-2000 rpm. Happens for about 3-10 seconds it’s not consistent. Sometimes it won’t stop unless I take my foot off the gas for a second. I had a misfire code for cylinder 6 so I replaced all the spark plugs and it’s still bogging. My best guess is the truck was used to the old spark plugs which were shot and now with the new ones it is getting too much air or fuel. Also around 0-40mph after that it seems to go away.
After the spark plugs I reset the KAM and no codes have showed up.

 

yes, and sometimes it won’t stop unless I let off the gas for a second then keep going. And only in 1-2 gear and rarely 3rd but not as bad. In my other reply I explain more

 

What did you use for your new spark plugs? Brand and part number would be helpful.

 

Spark plugs do not control the air of the fuel, but Autolite plugs can misfire. All vibrations and misfires went away when i replaced the Autolites with Motorcrafts.

 

I did use autolites

 

I used autolite plugs and now I see I should have used motocraft, will these spark plugs make such a big difference?

 

No. Could you identify a missfire if you felt one?