problem fiat punto

hi all ,lately I just come quai...I have a fiat punto 2002....the engine 12 8v......the machine to a minimum, but after 2500 rpm drops suddenly , makes high and low but only after 2500 rpm....I have done several tests....with four candles ,bobbine, the pressure sensor air, I checked the fuel pressure and it keeps on 350 bar....I checked the phase and it is ok....in the end I took another ecu that I had and nothing.. initially in the diagnosis gave me an error only P0302......that includes a little of everything..this morning I make another test with the phase sensor...I'll keep you updated....