Poor acceleration and fail emissions test
 

I am buying a 2007 Lexus GX 470 today, with 114 K miles, (no spark plugs change or water pump change) didn’t pass emissions test las February 2007 and Dealer will pass emission test before I buy it, but I notice that the card had slow response to acceleration ( It almost feel like to heavy, compare to the other 3 same cars that I drive), could this be due to a catalytic issue or mostly tune up.
I am closing the deal today any suggestions.
thanks