XLT. When it warms up, why does it vibrate a little when stopped at a light?

Define the issue a bit Further. does check engine light flash while stopped? check the basics is there air restriction and when where plugs last changed?

What is vibrating or shaking? Sitting still or driving along?

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balance on tail shaft was what? it sounds like the drive shaft and universal joints yokes were not scribe marked to be put in the same place causing the drive shaft to be unbalanced there are weights on the drive shaft EX. little metal bars welded to it try taking it out and rotating the shaft a bolt hole at a time or a universal joint cap + at a time to see if it helps also the universal joint could not be seated properly causing intense vibration at take off please respond and be much more specific so I can possibly help you figure it out with out actually seeing the truck LATER MAN!

Try releasing the gas cap and screwing it back in. If the relief valve for the gas vapor canister is clogged, you can build up negative pressure in the gas cap causing difficulty getting fuel at low RPMs.
If releasing the gas cap makes a difference, the fix may be simply making sure the canister orifice is cleared.

If there are no check engine lights could be a bad motor mount or two. Would have them checked. Try putting car in neutral and see if vibration disapates a little.

Up hill

Bad Ignition Coils
EGR Valve going bad



At a stop and hesitation

Clean MAF and Throttle Plate

CRC MAF Cleaner
CRC Throttle Body Cleaner


You can't leave spark plugs in there over 60,000 miles
Change fuel filter every 3 years along with the plugs

could be a loose belt, but more then likely a bad alternator. have a charging system performance test done.

Check your operator's manual. Make sure any and all fuses that have anything to do with the affected items are not blown and are working properly. If you can; check for loose fuse connections or wires. Hope this helps. God bless!

i still think universal join in drive shaft is dead or could also be the bearing inside deferential or transy ...
do you hear a funny noise or some thing unusual?

check the motor mounts