2002 impala runs bad

i have a 2002 impala 3.8 engine light came on and it has a bad miss so looked in to with my code reader says its a cylinder misfire detected-random cylinders.i put new plugs and wires on it, thats not it and i looked in to the coil packs thats not it, could it be bad fuel injecters, any info would help thanks

When does it start to miss? If it just seems to give out when you give her a good amount of gas, could be a clogged cat. My cat was toast, and She'd bog right out at 4 grand and I got multiple miss fires detected.

it miss's all the the time as soon as runing thanks for the info i will look in to that thanks

also i forgot to say is that i have a fuel leek on the fuel rail on the back side in middle where it hooks up to the line