motortuning omega 2.0 16V

I own an omega caravan b 2.0 16v but unfortunately it has almost no power in the lower speed range! now I’ve heard that by changing the lamda probe between 2.0 16v and 2.0 the engine power should be better?!?!? has any experience with it? or what other possibilities are there? does a chiptuning help something? THANK YOU! lG volll_gas_gas