Just to your cat ? . Two good indicators. Rotten egg smell and after a good hard run it will glow at night.

 

i have been having a similar issue with my zr2. half as many miles but I believe in my case the fuel system is at play. used to have an evap code and get a fuel smell which went away. stumbled under load with no power even when revs went up. Ended up hooking up the diagnostic scanner and doing a ckp relearn and the stumbling has reduced significantly but I know it is not what my other blazers were in terms of reponsiveness. I also did a diagnostic on the iac and egr, both working well. i would check fuel pressure and run the relearn.

 

Im not sure on this,but like on my dodge truck it'll tell you "bank 1,downstream sensor" which gives you the idea of which one is causing issues.

Guys do the check engine codes not tell us which sensor is the culprit on these vehicles? Im honestly not sure as ive always been around 1st gens.

Anyways,a idea to check the cat is this. Wait till dark (like pitch black) and take her for a good rump. Be hard on the blazer then pull over after its good warmed up. leave it running in park with the ebrake on and look at the cat. is it glowing? if so its congested and needs to be replaced.

 

im going to check the fuel pressure and the cat and get back to ya. the trans will shift at high rpms it just takes it for ever to get to the point to shift cause of the power loss.trying to get this fixed before winter cause the colder it is out side the harder it is to start thanks for all the help.

 

I basically have the same problem as Vonholt53 stated above, except mines a 98 blazer. Same 3 button 4x4 4.3. I know the fluid is dirty in tranny so I will start there. My thing is it loses RPMs at 3000 even in park! The motor bogs down and it sounds like vacuum leak, but I've no idea where to begin. Plugs seem good and theres new wires and fuel filter. Trying to avoid fuel pump, but it is going and theres a whining coming from it. Is there any ideas u might have?

 

the fuel pump is what was wrong with mine it runs like a beast now lol and starts right up every time

 

Answer to clogged cat, if you hear a lot of rushing air outside, or way more than normal it could be clogged

If the cat is clogged the exhaust may get louder as the engine pushes air out all the non welded gaskets and connections on exhaust. Lack of power too

That's how I knew when mine was clogged at 80k miles

 

I have a 98 blazer I just payed $550.00 for a new fuel pump, and filter. My sending unit failed so i replaced the pump which I thought was the problem with no power when accelerating, now my fuel gauge works yet i still have no power on acceleration seems to be real hot when I park smells like a burning smell hmmmmmmmm......

 

I have the exact same problem and its costing me alot to diagnose, did the fuel pump and filter my next is the trans. not sure were the next move is though..