So, I'm still on the battle to fix all the problems that the Audi a3 2003 that used to be from my grandfather (and now is mine) have.

I thought that the motor was taking too long to start because the battery was old, so I've put a brand new battery. But the problem persists...

Sometimes, when I'm driving the RPM gets crazy and oscilates very fast 1 mm above and down, and then it gets normal again. I don't know if this is related to the motor taking too long to start...

Any thoughts?

Thanks!

 

Kind of hard to diagnose, but have the fuel filter, spark plugs, air filter all been replaced recently?

 

try to use carb. cleaner and removal and the car will be fine
and check the air filter and change spark plugs but after you use the carb. cleaner