rough idle and bad emissions

i just recently purchased a dodge w150 with a 318. and lately it seemed lke the more work i do to it makes it run worse. i am thinking that my cat and/or egr valve and oxygen sensor are all bad. when its idleing it idles rough and almost stalls out i think that the more i do to it makes it run better so it needs more air but since the cat is clogged its creating a lot of back pressure which is making it run rough. it also faild emissions idle and under 2800 rpm. at 2800rpm it had 2215ppm in the hydrocarbon whereit should have been around 240.