F150 2003 5.4L Vibration throughout truck with acceleration

Motor mounts. You have bad motor mounts. They is extraordinary engineering behind all modern motor mounts. They are doing A LOT more work than you realize. And they go bad. Have your local wrecking yard confirm it. And and then ask the parts puller do it on the weekend. He knows how to do it for half the dealer cost. He does it every day. And could use the cash.... only pay the guy cash.
Or let your trusted shop do it. They will wsntbto replace hem all. Ask the wrecking yard expert if that is really necessary. He will be the only guy to trust with a question like this.

I have a 94, and mine ran rough until I had a new computer control chip put in. The dealer doesnt sell then anymore, so you would need to get a reconditioned one (is that the right word?) from an auto parts store. I had to get this done twice because the first one was bad so they swapped it out. There was one more thing the former owner did to fix a rough run situation, I will post it when I find the receipt. Also, it smoothed out even more when I changed out the motor mounts. WAY less vibration. I love to drive this car now!

I'm not sure exactly which vehicle you have so I'll try to be genera yet as specific as possible to help you determine the problem. I'm assuming here its a Gas Fuel engine.

1.) if its a carburetor type engine, You may need to adjust the RPM to increase or lower the Idle. Its commonly called the Ideal screw and adjust the air fuel ratio to stabilize the engine fuel mixture to increase the RPM.. its found on the Carburetor.

2.) ts fuel injected you will need to adjust the throttle body position to archive the same effect.

if it has a distributor , you can turn the distributor as well to adjust the RPM.


rough idling is usually caused by Mounts, since you changed yours the next most likely issue is the RPM itself or idling speed / rpm. If its to low you ill have that issue.

other possible cause is the distributor points (if any).. bad plugs, bad plug wires.. but those cause other issues while driving as well.

The only thing I can this is a vacuum leak, either a hose or egr valve.

I hope this helps!

on the accelerator cable in the engine compartment at the intake should be a little screw that will give you a little play for the idle

Well, kind of short on description, issues typical in this complaint are misfiring and U joints.

To emininate the engine, does the vibration happen on power braking, without the vehicle moving?

sound like the u-joints in the driveshaft. Lay under the truck and where the u-joints are try moving the driveshaft up and down. If it moves then the u-joints are bed. This will cause a tremendous vibration under a load and the faster it spins it will smooth out.

Increased vibration from a vehicle indicates worn out engine supports. This vibration often disappears when revving the engine high, but is very noticeable at low revs.

You can have these inspected and possibly replaced to reduce the vibration cominf from your engine.

Hope this helps.

check the drive shaft between the intermediate transmission and the front transmission for miss alignement and defectivness of the telescopics system of this shaft. we had about the same problem on our 1996 same model...

I would venture to say your exhaust is hitting your frame, or, you may need new motor mounts. The exhaust is what I would lean toward. If you can imagine your exhaust sitting under your vehicle, and the fact that the vehicle has a little age, the motor mounts probably give a little, causing the motor to move slightly on acceleration and deceleration, thus your exhaust is going to move, and may be vibrating on whatever its touching. Good luck.