2.4 random missfire

[chayito95]

new guy here

2.4 l oldsmobile alero automatic

the problem.. random missfire, sluggish at wot sputtering. regular missfire as i have seen on this site.
So here is what i have done, bought new coils and plastic cover. checked injectors they check out fine.

engine blew there after.

Bought new engine, again same problem, bought new pcm fixed problem temporarely. so i went over everything agian from spark plugs, coils, boots ICM crank and cam sensor, coolant, tps, iac, and o2 sensors they are all within spec. Yes i used a voltmeter. I also checked for vacum leaks found none i checked the cat, thought it was clogged ran it with out it and no change.
so Im basically stumped i dont know where else to check.. i havent gotten around to checking the codes the new pcm has thrown cause the car wont make it into town to my nearest autozone.
any ideas would be much appreciated

thanks