99 Blazer losing power-code P0404

Just had Blazer inspected. Mechanic said rattling sound at low idle was insides of cat. conv. coming apart. When I looked underneath, sounds like thats where rattling is coming from. Recently been losing power, most significantly going up-hill. Have a Power Programmer that gave me a trouble code P0404 when Service Engine Light came on. Cleared the code and light went off. Any idea why still losing power? Even with Programmer installed, no power on acceleration or hills. Usually, the Programmer really firmed-up shift points. Thanks for any advice or info. Also, just removed and cleaned K&N air filter with no change.

Bob

Code P0404 is for egr pintel position.
Remove EGR valve and check for a carbon ball under the plunger.
MT

Do I need any special tools to remove EGR valve? or sealants or gasket maker goo or anything else to replace it? What kind of solvent can I clean it with if I can get it off? Thanks.

Ok, tore off EGR valve and tried to clean carbon out from around end of pintel. Didn't seem like pintel was stuck or anything. Put EGR back on and still no power on acceleration or hills. Seems like it's hesitating more with rapid accel. Don't know what's doin' it, but the Service Engine light isn't coming back on either. Any ideas, let me know.
Bob

the P0404 is not related to the power lose. The cat coming apart internaly is most likely your problem, to much back pressure. Check out the performance thread for advise on high flow cats http://www.automotiveforums.com/vbulletin/forumdisplay.php?f=2110

Thanks Eric,
Do I need a degree in welding/cutting to get the cat off since the flange bolts are probably corroded/rusted on? Or should I leave this to the muffler shop?

Depends on the type of cat you get for it.
Some are weld on and some direct fit OEM type cats will just clap on.
If a weld on or non direct fit the muffler shop is the way to go.
Even if cat is rattling it is bad but it may or not be the power lose problem.
Always check back pressure to see if cat is the power lose problem.
And remember engine running problems can cause a cat to go bad.
Always go over tune up end and secondary ign. . Good Ac delco plugs?
Another good test is for proper running fuel pressure on the road and after it has run 20-30 minutes.