so i been working on the blazer in between having a new baby and a new job and i cant get the buger to run right heres whats going on, has no power at all when u step on gas i mean no power at all,if u floor it, it takes some time but it gets up there and when it shifts it will break tires loose on my dirt road.
idles fine real good infact since i replaced the fuel pump with a ac delco version and got away from the airtex,thought it was on its way out as i been having problems with it in the past. changed spark plugs with delco 43ts (got 60-70k outa some autolite plats) and today cleaned egr it was clean and free of carbon as i have a help gasket installed. tried to check leak down but discovered my pressure gauge stopped working wont register anything so cant tell if its leaking down but oil smells like oil not gas. intake is clean on passenger side but did check when had upper plenem off and fpr is not leaking per visual inspection.....im outa idea as its not throwing any codes to try and track down hopefully with some input from u guys ill get it going again......

 

Does it run worse when warm? Im thinking it has something to do with an O2 sensor or the cat. Both of which don't always throw codes when bad.

 

if the intake is clean then it is getting washed out, find a working pressure gauge. I had a leak that wasn't visable, however replacing the spider solved it.

 

I`m thinking clogged cat also

 

runs the same when warm or cold, cat is only like 4 years old and it has a lot of exhaust pressure, last year it passed emissions with flying colors don't know if that makes a difference. bad thing is its all welded and i hate to cut it off and not fix the problem as i cant weld nor do i have the means to learn

 

Prob not the cat then.

 

I still think cat
the exhaust still needs to get out so pressure should be there
get somebody to work the throttle while you stand at the tailpipe ,the exhaust sounds extra muffled when they clog up
My sisters Monte Carlo SS threw no codes but I thought I was going to need to push it up a small hill on a test drive
Her Monte was still under warranty when it plugged

I am not sure if it is true but you may want to try
Years ago a guy told me if you warm it up and hit the cat with a good stream of water to suddenly quench , if it stalls the cat is shot

 

My first thought was cat, that happened to me once i just had to putz around at 30 mph till I figured it out.

 

the sound isnt muffeled coming out of the tail pipe its as loud as it ever was its got a 2.5 inch all the way back with a flowmaster 40 or 50 on it

 

Have you replaced the O2 sensors? What brand are you running?

Had this same prob on my '85, and on my '05 crown vic. The Blazer didn't throw a failed O2 code, but the vic did. New Bosch O2 sensors fixed them both.