Sputtering problem

NO check engine light starts great everytime idles ok and it never stalls out. It revs up fine you put it in drive feather the pedal it runs fine. But when you push pedal in further it starts hesitating and breaking up bad like its loading up or running on few cylinders. Ive tried plugs wires and dist. Cap no improvement seemed like it ran better in cooler weather But that might be coincidence. Dry or rain no change in performance. Not sure what to do next don't want to spend lots of money and parts chasing after this problem.