Vibrations every other Seconds

[mprus]

Hi, I have a 2004 Mazda 3 Gt and I recently wanted the dealership to service it and it still isnt performing right.

The problem arises when stoped at a red light or idling, there are random shakes/vibrations and or every 3-5 sec slight vibrations at idle. When put into Neutral, the shakes are greater then in drive. When in Park same shakes/vibrations oocur at idle. When in drive slight shakes but not as bad as N/P.

Went to the dealer and they say my car is fine, but I know its not.

They cleaned the coils and changed the spark plugs
New engine oil
Cleaned out Air filter
New throttle body
All engine mounts and transmission mounts were checked and are okay they said

Any Ideas what it can be ?

Thanks

[Tozer]

My 07's always done it, figured it was somewhat normal

[Wes08M3]

Purge solenoid valve has been known to cause vibrations at idle. There is a test procedure in the shop manual that can be used to determine whether it's working properly or not.