Need help please! Code po301 misfire on 1. I have changed spark plugs , wires, coil. missing during reg. speed of 60 mph, jerks like crazy when i slow down to 30 to 45 mph. what else could it be?

 

Some questions first.
Did you make sure the plugs you installed were set to the correct gap?
Unfortunately many aftermarket coils are not the best and come with their own problems. Are the symptoms the same with the old coil and the replacement ?
Did you replace the plug wires one at a time or all at the same time? Could one of them be in the wrong place?
You don't usually get a single cyl misfire with a fuel problem, but did this problem show up a short time after purchasing fuel?

 

Yes plugs are to the gap. Coil new from Napa,Motorcraft plugs, Motorcrft wires, fuel filter changed, Now what do you think " Hanky " ?

 

I think you may have more than one problem.
Did you have the exact same results with either coil?
What engine do you have in it?

 

Same code came back up ! PO301. I have 3.8 engine v-6

 

Have you ran any type of fuel injection cleaner thru your system? You could have a dirty/bad fuel injector.

 

You know I completely forgot about a bad fuel injector,but the part that is puzzling is what is going on when you get those symptoms when slowing down. If I understand what you are telling us , it sounds almost like the ignition system is cutting out.
I would suggest you check all electrical connections starting with those at the battery and work your way from there. At least you will eliminate those possibilities. Can you do that?

 

......and don't forget those ground connections.

 

Don't know how involved you want to get on the misfire problem, but one of the possibilities could be related to the valve train.
Anything from a broken valve spring to a valve seat that as sunk are things that could confine the misfire to a single cylinder after the ignition system has been ruled out.
A good scope man/woman could confirm these, and also if the valve cover was removed to see that cylinder's valve operation could help isolate a problem there.
That's why I questioned your willingness to get very involved in it.

 

Just like a lot of other vocations some problems won't leave you alone.
When you changed the plugs and wires do you have wires that are running parallel to one another namely the wire for that #1 cylinder that is reporting a misfire?
If so, try to separate that wire from any others and see if the misfire goes away.
If possible separate the wires from one another as far as possible to prevent a mutual induction misfire condition. That just might be the problem with the jerking on decelerating. Let us know if that helped. Thanks.