I have a 2004 Audi A4 3.0 quattro. Never done any mechanical change or upgrade changing the car from stock. Only change is a 20" wheel I have on it.

My problem is. Driving in the city with speed around 35-55 mph the RPM meter keeps going up and down between 1 and 3 .... its like the car was changing gears all the time but the gear never gets changed.

second problem is when driving in a highway w/ speed above 60mph and I need to slow down for some reason and when I go to get up to speed again, the moment I get close to 60 mph and after 60mph the car shakes for as long as i keep pressing the gas pedal. I have no idea what the problem is, does anyone have any idea what could be the issue and if by anyhow they are related to each other?

Thanks a lot