2004 4 door Blazer LT 4x4 4.3 (that's a lot of 4's, never realized that lol)

Over the past few days I've noticed a lack of power when trying to accelerate. First noticed it when pulling onto the road from my neighborhood; pulling from a dead stop and onto a 60mph road. Then I started noticing it in town when taking off from traffic lights; even just trying to easily accelerate, it seemed to just bog and not have the pep it did maybe a week ago. It doesn't spit and sputter at all, in fact it purrs like a kitten, just doesn't seem to want to move out of it's own way. It seemed to be gradually getting worse, then this afternoon on my way home from work, 60mph 2 lane road, I tried to overtake someone that was doing about 50mph. I laid into the throttle and got over to pass, and it had to take me at least a half mile to get up to 60mph... Came upon another 45mph car in a 60 zone and attempted to pass then, and this time the truck just refused to accelerate... after having it floored for about 10 seconds and barely making any headway, I backed off and just pulled back in behind the car and putted home at 45mph... and by "putted" I mean drove grandma slow lol not like the engine was puttering.

About 2 months ago I put in a brand new fuel pump and changed the filter while I was at it. I've have two codes throwing right now, one for the evap vent system, and another for evap pressure little/no input or something like that, but I've had those on for quite some time, and I've been chasing that issue, but up until a week ago it was running just fine despite those codes. So I don't think those are effecting the running of the truck.

I want to start off with just plugs, cap, and rotor, but part of me thinks that that's not the cause either, because in the past on other vehicles, bad plugs or bad cap and/or rotor has resulted in misfire and a rough running engine in general. It's not showing any signs of that, just the no power.

Oil pressure stays good, there's no overheating, doesn't seem to matter if the AC is on or off.

Other possibilities I can think of:

*bad MAF (just swapped it about 3 months ago because it was throwing a code for it; changed it, code never came back, and fuel mileage improved)
*bad O2 sensor (changed the faulty O2 sensor at the same time as the MAF, same story with it; code hasn't came back, fuel mileage got a little better)
*clogged cat. converter (165k on the vehicle, can that be bad already?)

Any insight? Suggestions?

 

Well, doing a little reading, and comparing symptoms with others, I'm pretty sure it's a clogged cat converter... so, either tomorrow or the day after, I'm going to gut it and see what the results are. If it helps, then maybe I'll throw a new cat on it... maybe not... no emissions tests here in Florida lol

 

i'm with the cat being pluged also - before gutting the cat and destroying it pull the pre cat ox sensor and take it for a drive if it does better the cat is pluged - if worried about hot exghaust gasses on the floor pan duct tape a tin shield on the floor pan

 

yeah I thought about doing that, I might give that a shot over my lunch break at work tomorrow before I crawl under it in the afternoon and hack it up

bad thing about a 4x4 is the way the pipe on the back of the cat has an S bend that curves over the torsion bar crossmember, so I can't just unbolt the flange and gut it... that's how we did it on my dad's 95 Sonoma 2.2 2wd. I'm going to have to take a sawzall to this one in front of the cat, then just unbolt the flange and pull the cat assembly out. gut it, then put it back with a coupler that slides over the original piping

 

well the cat was definitely the cause! gutted it and the thing runs like a bat out of hell now!