its a 2000 4X4 with a 4.0L 6 cyl engine.
it running very rough at idle, rough when cold but when the engine is finally warmed up it runs even rougher, no power, shakes and shudders under a load.
i brought it to a mechanic and he checked wires, plugs, coil pack, compression test and vacumm test all passed.
I have also noticed when the truck is good and warmed up a sulfury smell comes out of the tail pipe.
could this be a catayltic converter problem? what i have missed in trouble shooting? would a ignition module be the problem?
getting ready to pull my hair out!!!

 

Does it only do it at idle or all the time?

 

idles rough all the time. runs terrible when driving, shakes and shudders.

 

Sounds like a clogged cat converter...

Also clean your MAF and check your oxygen sensors while your at it.

 

thanks for the info and help!

i'll check and clean the MAF. I'm going to check the resistance on the ignition module also.

 

Sorry to hijack the thread but how does one check an o2 sensor? My truck has 168k on it and i'm sure they have never been replaced. Also I have never seen the trouble codes for them come up when I check for codes.
Thanks

 

Minus reading data directly from it and making sure its operatin gwithin parameters.. the only 'real' way to check it withotu the handy dandy computer tools is to unscrew it and make sure it isnt looking nasty as all heck.. thats about the best assumption I can make fo rthat. if they are still stocker son yoru truck, or at least over a hundred thousand miles.. I would probably recommend changing them.