Engine Vibration

[Jayk1]

I have a Toyota Previa 2002 2.4 CDX Automatic which has done 165,000 miles that seems to have a problem of engine vibration at idle when in drive/reverse.  I have has the vehicle from new and is services regularly. This vibration is particularly annoying when stopped a red light and the gearbox is in drive. The vibration goes away once the vehicle is moving and drives normally. The vehicle has had all its engine mounts replaced and a new exhaust system including catalytic converter and 02 sensors. These changes did make some improvement, but there is still a very distinct vibration which is felt through the steering when vehicle gear is in Drive or Reverse and the vehicle stationary. The vibration goes away or is not felt when the vehicle is moving (i.e. moving faster than 5mph). The vehicle had a new automatic gearbox replaced at 112,000 miles by a gearbox specialist. It has been checked by them and they say the gearbox is fine and is not the cause of the problem.  All fluids have been replaced and checked to at correct levels. Full service done i.e. oil and filter changes (oil filter, air filer cabin filter including spark plugs plugs, tested for any misfiring and none found).

I have taken the vehicle to several garages and they all seem to be baffled. Has anyone got any ideas as to the cause of the problem?

[Paulscarbs]

Check the steering box for worn components.

Also check the drive shaft couplings.

[Jayk1]

Many thanks for your reply.

When the vehicle bonnet is open and the gear is changed from Drive to Neutral and Neutral to Reverse one can see the engine is vibrating more than it should. This vibration may be putting more stress on the new new engine mounts (all 4 replaced recently at the same time). There does not seem to by much play in the steering. I am not sure what you mean by drive shaft couplings - is this the same as CV joints. Both front sides were replaced about two years ago when detect noise on full lock turns right and left. There is no ticking noise on full lock turns.

[TomdeGuerre]

You don't say whether you get the problem when the engine is cold ie engine speed probably higher.

It might be the IAC (Idle Air Control) valve and suggest you have a look here 

http://www.autozone.com/repairguides/Toyota-Pick-ups-Land-Cruiser-and-4-Runner-1997-00/ELECTRONIC-ENGINE-CONTROLS/Idle-Air-Control-IAC-Valve/_/P-0900c15280261b8e?CJPID=3193631&cmpid=cj