i just bought a 98 Red Chevy z71 with a 5.7 350 and it drove home fine, but the next day i went to start it and when i got on the gas and it stalled. it holds an idle no problem but touch the gas and it stalls or runs really rough. so i changed the air filter, plugs, wires, dist cap, rotor, and the camshaft pos. sensor. after all that it was good for about 3 miles and now back to its rough ways again. please help