Hello, I need some help diagnosing my truck.

It is
-2004 2wd 4.6 v8
-automatic
-126,000 miles

So the other day I was driving and my truck started stuttering between 55 and 70mph.
It got real bad. My engine light turned on and was in the blinking mode.
I could hear valve knock as well.

I turned off the truck checked the oil and it was ok, when I turned the truck on there was no blinking engine light just a solid one. I decided to keep driving after a quick search showed it might be the coils. When I got to the mechanic indeed a coil was bad. I had the mechanic fix it and do a oil change.

Now the engine light does not turn on but every so often I get the same sputtering and valve knock at the previousely mentioned speeds. The situation principally happens on uphils also. Street driving would not show a problem but once I get on the freeway its a diffrent story. Also it dosent do it all the time at those speeds. It sputers ramdomly, I.e. I will be driving 65 for 10-15 minutes and it will sputter for >3 seconds and go away.

 

Also, the mechanic seemed to have fixed it as the severity of the problem is about half of what it was and its not throwing any codes

 

how many miles on the plugs?

 

All of them, what worries me is the valve knock. Will bad plugs/misfires cause valve noise though?

 

Well I would start by changing the plugs and the rest of the COPs. The worn out plugs have stressed the COPs till they are all going to go one at a time. What do you mean by valve noise?

 

Yeah, when the engine stutters I get a noise as well that I can say is what a valve would sound like. Just a quick tapping. I had a bad/bent valve on a old foxbody mustang and it sounded exactly like that

 

Sounds as if you need some serious maintenance. I would do the plugs, COPs, clean the throttle body and MAF, then see what I had.

 

Ok so I hit 80mph today. VERY hard sputtering, engine light flashing on/off. Slowed down to 60 and evrything went away. WTF?

Thank you bluejay for the help.

 

Almost sounds like a lean condition. When was the fuel filter changes last?