New engine cover = problems?

[ChrisGti]

Hi Guys, Fitted a new engine cover yesterday as my last one snapped but its changed a few things.


The engine now has a rougher idle
The steering and pedals vibrate slightly
Turning the air on changes the tone of the engine

On the plus side i was getting an easy 60mpg last night doing 30mph in 4th.

I've checked all the pipe work and cover mounts but all appears fine.