my 03 cooper shows wrong amount of gas i was driving and it was showing 60+ miles and it suddenly stopped because it ran out of gas... any ideas how it can be fixed easy??

also between 2000-3000 rpm car has almost no power in acceleration what it can be?

 

The gauge reading incorrect could be a bad fuel sending unit which is located in the top of the fuel tank or a bad float or a bad ground.
So when you accelerate is the lack of power only between 2000-3000 rpm in any gear? Has your fuel filter ever been replaced? Your MAF could be dirty too. Do you ever get a SERVICE ENGINE SOON light?

 

i believe its on 2nd gear and no i dont think so i didnt change anything yet i just bought it and yes it lights up Service...