Possible wires installed wrong or plugs not gapped properly. You don't say what kind of car so I cant tell you the firing order. Check you put the right wires on right plugs. ALSO- If you have a timing light or access to one- Check timing! If it was timed/tuned with old plugs for several years (it happens, my smog guy does it to pass me), then it might have been changed to accomodate the old plugs wearing down. Plus a hotter burn/spark will automatically change your compression and therefore your whole burn sequence. I put in 'fancy' platinum plugs in my Bronco once and it refused them, running terrible. Had to put in new 'old' type plugs and ran perfect. Go figure. Dokter Denney
the transmition ,is probably not adjusted to the spark plugs,or their not the right spark plugs
Yes. Bad spark plugs, bad spark plug wires and a bad distributor cap are the common causes of rough idling. If it has been a while since you changed these components, do so.
as a result of bad spark plugs
Maybe when they put the spark plugs in they were not gapped right or they maybe the wrong spark plugs.
Old spark plugs can make a car misfire, run rough, and not fire at all.
Poor performance, hesitation and rough idle could be signs of worn out spark plugs.
Change the spark plugs and wires... Change the spark plugs and wires...
Spark plug wires? Coil pack? Dirty injector? Spark plug wires? Coil pack? Dirty injector? Spark plug wires? Coil pack? Dirty injector?
Yes, bad spark pugs or plug wires can cause the engine cylinder to misfire which will cause the engine to vibrate.
Check/replace Rotor Check for spark at plugs
I would replace the spark plugs after 50K, the wires and plugs again at 100K.