I was having multiple miss firing on my engine at 1750 rpm upon cruising. they called it bucking. It started after I put new plugs in (champion). I got all my plugs out with out break one.
I have seen many posts where people were talking about miss fires and I thought I would put this up.
After many parts and guess work I finally broke down and went to the ford dealer. I was having p0300 codes and random miss fires. then I got a p0303 and p0304 code which indicated the 3 and 4 cylinder miss firing. Turns out the champion sparks plugs dont work well on this engine and I had to have them changed again to the motorcraft oem plugs to the tune of 310.00. I have put new cops and several injectors also(which did not need to happen). So use the motorcraft oem for this engine, it appears to be very sensitive. PS I have 99k on mine at this point with no other problems.

 

you got lucky....if you have a misfire with the motorcraft oem plugs, you will be paying them for the extraction and stuff... to replace a bad champion? a caveman can do it...

 

See photo of my Champions with 40 miles YES just 40 miles or 1 hour of run time. Missed like nobody's business!!!!!!!!

 

Ok...So which Champion Plug were you guys running?

-Ted

 

Champion 7989 used but FAILED. Replaced with Autolite HT1. Now that I know how to properly replace them and they ACTUALLY work, I'm not concerned with the 2 piece design.

 

a year and 15,000 miles has passed, my champion still working like the first day. all good.

 

It seems like the champions are hit or miss, my mechanic told me to use the new motorcraft plugs that don't break apart so I'll be seeing if I can get them changed today--my truck is also bucking and is getting worse.