Thanks in advance for any response.

I have a 2000 Blazer that's been acting up recently. It started off with occasional misses/studders from the engine when I was going up a hill, or accelerating hard. Progressively got worse during the week, so I looked into it and thought it could be the fuel filter/plugs/wires.
Right now mileage is at 160k. I've had the car for about 75k miles and I've never replaced the fuel filter, just from inexperience. I didn't even know it existed. So I'm leaning towards the fuel pump being the culprit.
So I first changed the fuel filter, took it for a test drive and it was instantly worse once the car warmed up. So I moved on to changing the plug wires. Automatically better for about 4 days.
Things again got from good to bad, and I decided to change the plugs themselves. Instantly a huge improvement. Again, about 3 days later, The truck is sluggish when accelerating from idle, it sputters up hills and has no pick-up whatsoever. When in idle it runs perfect. And the pattern is that once the truck warms up, it gets 5X worse.

Any one know what the next course of action should be?

 

Check fuel pressure? Possibly fuel spider or fuel pump?

 

That's what I was leaning to, but I just talked to one of the local shops here, and they're pretty convinced that it's a bad catalytic converter.
Anyone able to give their opinion on that?

No check engine light is on.. and one minor detail I left out earlier, when I accelerate pretty hard, not flooring it, but close to, I hear a faint rattling noise coming from somewhere, but I can't pinpoint where.

 

Update:

I just got back from the shop where they hooked up the computer and the mechanic said that the catalytic converter doesn't look like its the problem. The temps from both sides of it are pretty even.

He did mention that he personally thought that its either the spider injector, as mentioned above, or the Mass Air Flow.

Has anyone had these problems before?

 

Unplug your Mass Air Flow Sensor 'before' starting the engine. Hop in and take it for a test drive, if its dirty than you will see a big improvement instantly! If thats what it is, then your MAF is simply dirty. Clean it up, and problem solved!
There is a thread in the DIY section that tells you how to clean it.
If thats not it, Check for a dirty EGR valve before you go tearing into the injectors.

 

Thanks for the help, I'll try that next and give an update on whether or not it worked.

 

Update:

I cleaned the MAF sensor last night and it seems to have helped the issue, but not completely taken care of it. I'm hesitant to say that the MAF was the problem, because one of the only constants with my sputtering problem is that its gets alot worse when the engine is warm, say after about 10-15 mins of driving.
Today when I drove to work, it was about 36 degrees out, which I would imagine, would make it drive a little better for a little longer because it's not getting as hot, as fast.

Also, just got a code reading. Random Cylinder Misfire. That's the only code that comes on, No engine light.. though, ever.

I'm finding a few threads on this that are similar to whats going on with my truck, so I suppose I'll take a look at cleaning the EGR Valve, the MAP Sensor, and then replace my cap and rotor with AC Delco parts.

Any other suggestions?

 

Ok, so I cleaned the MAF sensor, and also the EGR valve, still no luck. Moving on to the fuel pump/pressor/relay/regulator.