Strong Engine Vibration...3400-3900RPM Need some assistance please!

[TGPilot]

Craig...

Two questions for you.

1). Should this be done right away (has been 6 months like this) to avoid possible engine failure?

2). I know the timing belt needs/should be done at the same time...can this be done in the car or should the engine/tranny come out to do it. Obviously it would be easier access...but is it necessary to remove the engine/tranny?

Thanks!

-Kenny