Please could someone help me before I end up being ripped off by several mechanics for a hit and miss guess?

I own a 2003 '53' A6 2.0SE CVT but recently I have started to notice engine vibration when stationary at traffic lights or when I start the car. It stops slightly if you go from D to N. Makes no difference if the engine is hot or cold.

There is very little movement on the rev needle when I watch it. So would assume coils and spark plugs are ok?

I have also noticed a little vibration at say 70mph but assumed that is due to needing the tyres re-balanced? Or could this be linked?

When the engine is cold from start the engine almost sounds different, as if it is a really old engine. Best way to describe it is as if it's almost a diesel! If I lift the bonnet with the engine warm and running it certainly doesn't sound like it use to when I bought the car 4 years ago.

A couple of years ago I did have the alternator replaced with new belt and pulley. Could it need adjustment? Pulley faulty? Although there isn't a rattle!

Months ago, the car didn't want to reverse when parking, it just jumped/jerked. Then I went shopping, returning to the car later, when I started it the engine fan came on, but on full as if the engine was hot. I can't be certain but the vibration may have slightly started after this!

Sorry for the long post and several questions.

I look forward to hearing from you.

Many thanks,
Adam