I have 2005 Volkswagen Fox 1.4 liter petrol engine. Around a month ago I started to notice strange thing. When I switch from 1 to 2 or from 2 to 3 gear the engine starts to stutter(This happens at around 2000-3000 rpms), however if I give it more gas and raise rpms over 4000 gear switching works just fine without any problems.
Also what I have noticed is that the engine is strongly vibrating(Especially when it's warmed up) in neutral gear while standing still. And sometimes when on idle engine simply drops rmps and goes off. The vibration goes off if I press gas slightly when in neutral gear. Sometimes when starting up the engine goes off immediately because rpms drops before reaching 1000.
One more thing that is really strange and quite frustrating that on average it consumes at least 10 liters of petrol which is quite a lot for a 1.4 liter engine.
Do you guys have any idea what could be wrong? Any answer is highly appreciated
UPDATE This was spark plugs problem. I have replaced spark plugs and now it's running smoothly.