camaro acting up

I have a 95 camaro with the 3.4
a few months ago the cat converter plugged so i took it out.so now its running without one.since then it just wont run like before.i changed the spark plugs/wires,ignition coils.it starts right away,the thing is that when i start driving it runs really slow,i can hear the motor forcing itself but it wont go faster.after afew minutes of driveing it will go to the speed that i want but slowly.i can feel it shift from 1st to 2nd,hard
I thank you for youre help