blazer runnin like poop

so i have a 99 blazer 4.3 and lately its been runnin like crap... idles fine and is better in lower rpms and once it gets higher in the rpms it starts missin and spittin and spudering and i cant go over 60 mph. the problem has progressively gotten worst and its almost to where i cant even drive it. any help? sensor? mass airflow? cat backed up? thanks in advance

has it sat for along period of time? fuel maybe? plugs old? plug wires? possibly the injectors could be crap. soo many things to trouble shoot.

drive it daily.. i think im gonna go through and change plugs and wires to start off the trouble shooting process (yay! lol)

same thing my daily was doing. I finally replaced the distributor and everything seems to be better now

check the vaccum to the fuel pressure regulator, my brothers blazer fpr wasnt even working because the vaccum hose was rotten off

thanks guys!

well figured out a couple problems with it. threw codes for: egr valve, and take pressure sensor... the cat is good. and effin A that egr valve is expensive!!

indeed they are no joke......