I posted on this issue a while back and I still have the same problem. However, I have done alot of things to the truck since then. I have a 2004 F150 supercab 2 wheel drive. It has 90,000 on it.

Several months ago I had an intermittant vibration. At first I thought it was an engine issue. I had it checked at 2 different dealerships and there were no codes and they couldnt find anything wrong.

Since then I have had the plugs changed out, the injectors cleaned and the 90K sevice done.

This problem doesnt happen very often. maybe once every 2 weeks or longer.

Yesterday it happened for the first time in several weeks.

When it happened this time, I was going down a long hill at about 40 miles per hour. I decided to slip it into nuetral and turn the engine off. The vibration did not go away. Now Im suspecting either drive line or suspension issues. I have also had the tires balanced and rotated. So Im pretty sure its not tires. I do need to replace the shocks. And it could be related to bad shocks. However, the conditions that it happens in are so different.

After it happened yesterday going down the hill, I did what I normally do, pull over turn the engine off, restart it and go. That for some reason seems to help. When i got on the freeway it would vibrate at 60 mph but not so bad at 50-55. Any ideas would be greatly appreciated.

 

I have a similar issue, and think it is driveline related but havent figured it out. This weekend I had a long road trip and on a couple of occassions at around 80MPH I experienced pretty violent vibration that I could feel on the steering wheel and floor of the truck, while it was happening I put tranny in nuetral and it would actually get worse, put it in drive and it would settle a bit. It happened a couple of times in a 10 hour trip but stop happening just as quickly as it begun. I also have an 04 2X4 with 82000 miles. My tires and shocks have less than 5K. The vibration appears speed related but cant figure out why it randomly starts and stops