Have a 2001 Gti 1.8t, engine has been on for a while, had the coils changed and spark plugs but it still revs high when i start it.Its like it takes the engine a while to warm up. Engine bogs as well when i changed from 2nd to 3rd and step on the gas. Had it diagnosed and code came up that fuel was to heavy?? Or something any suggestions, don't know if it might be the O2 sensor???

Don't want it to break down on me,...again.

 

How high does it rev when it's warming up? Could be the throttle body, fuel pressure regulator or an O2 sensor as well. If you could get the exact code number I could probably help you better.