I think I have a bad coil from what I been reading. In over drive under normal cruising speed sometimes it bucks and jumps unless I mash on the gas. Now the miss is noticeable even not in overdrive.I can rev engine and feel it. I have no check engine light yet. will a scanner still tell me which coil is bad if there is a bad one? How can I tell which one it is?

 

Have you checked for codes? Your truck should throw a code which should tell you if there's a misfire and which cylinder or cylinders are guilty

 

It will post a fault code ONLY when it gets severe enough to go over a calibrated threshold.

Mild misfires must be diagnosed by looking at the Mode $06 misfire data with an appropriate scan tool.

 

Had my buddy hook his scanner up to it and it shows misfire on cylinder #3. I assume that's the culprit.

 

And I've learned something new today.
I am assuming by appropriate scan tool you mean something better than an Autozone cheapy? What do you recommend personally?

I see the OP got a result of cylinder #3 misfire, what would the next move be? Testing the coil for resistance?

 

Next step would be to change all the spark plugs if they have more than 60k on them - I'd at least pull #3 and look at it, replace the coil. Resistance testing is meaningless.

 

I bought plugs today and am going to pick up a coil after work tomorrow.

 

I hope you bought MOTORCRAFT plugs - torque them to 28 ft/lb and do not use antiseize. Use dielectric grease inside the coil boot.

 

I did buy motorcraft plugs. I don't want to use anti seize? Thought I was supposed to?

 

The standard recommendation now is to not use antiseize to help prevent them from blowing out because there are only about 4 threads holding the plugs in.

However, when I replaced my 02 5.4 plugs at 119k miles, I did use anti-seize. It now has 142k on it with no issues. I plan to go back and check to make sure they are still tight but I haven't yet.

 

http://www.blownoutsparkplug.com/

FAQ's #51 and #52.

 

I had the same issue a couple years ago, it was a blown sparkplug on the #3 cylinder.

One Helicoil and new spark plug later and I was up and running.

 

You are lucky the helicoil is still working - the only 2 inserts that last are Timesert and Lock N Stitch.

 

Fully half of the inquiries for renting my Timesert kit have come from guys with a newly blown Helicoil, Dorman, Save-a-thread, etc and similar $30-40 "repairs".

That tells me all I need to know about them.