So for 2 days in a row while in 5th gear on the freeway my valves have started to chatter wildly and loudly when I put my foot on the throttle, then it will go away...... down the road it will do it again. Threw a code yesterday misfire on cyl 4. Doesn't do it around town. Didn't do it going up a steep mountain for 5 minutes of ascension. Just does it on the freeway randomly. Seems like when I am going down the road for a bit it loses fire on at least that cyl... I was thinking maybe one of the coil packs is going down. The timing is sketchy though on when it chooses to misfire.

 

i had that issue on cyl 3 a few months back and it was a bad spark plug. i would start with new plugs since they are the cheapest and go from there.

 

Wish it were. I've replaced the plugs and wires on the truck.

 

New info, it misses at just a very light touch of the throttle in any gear, which is why I may have first figured it out in 5th on the freeway. On the freeway however it won't stop missing and valves chattering until I downshift. Then I can shift back up and things are fine so I must be making the coil pick back up or something.

Also, after sitting it misfires for about 3 or 4 seconds when ice cold from a dead start.

 

try coil pack? theyre expensive

 

Well I swapped the ignition coils, so if it misfires and it is on cyl 4 again it's not the coil. I won't know until I throw the code again, but it still has a general light misfire in it. I can feel it when just barely on the throttle and it is obvious at idle when you listen to it.

 

I replaced the plugs with E'3s about a year after I got it. The #1 plug wire would not stay snapped onto the plug head. I took the plug out and placed it side by side with the oem plug and I noticed that the seat of the E'3 plug was higher then the oem. The boot of the plug wire wasn't going on completely cause the E'3 plug was sitting deeper in the hole.. Check that out if you have the old plugs still.

 

Mystery solved, These two plugs are from cyl #2

This is the third AP104 Autolite plug to fail on me in 3 months. All different issues in different cyls, but all insulator failure.