idles really rough sometimes

[aguyfromky]

hey guys, new here from kentucky.

i bought my truck back in early june of this year. 130k when i bought it (137k now) very clean ext cab 4x4 paid 5500 for it. had a ses light when i bought it for catylist. found it had bad intake gaskets along with stopped up cats. a buddy replaced the gaskets while i was on vacation and i replaced the ypipe with one off a low milage wrecked truck when i got back. then i got some 02 sensor codes. the truck had always ran rough when it was warm, not hot, since i had owned it. i was tired of dealing with the 02 sensor codes so i took it to my local performance shop to have the ecm tuned for a little extra power and to shut off the rear 02 sensors thinking thats why it ran rough sometimes. havent gotten an ses light since then and have a good amount of extra power, gained about 25hp according to the dyno. BUT... the truck still runs rough when its warm, doesnt do it when its cold or hot but usually every time when its just warm and seems to be getting worse. kind of not sure where to go from here besides a vacuum leak. and the guy that did the intake gaskets said he looked at the intake the best he could and couldnt find any cracks. any help on what to look for would be greatly appreciated

[aguyfromky]

also not that it matters but only other mods were a cold air intake and a flowmaster delta 40

thanks

[dcheeseman]

Does the tach jump up and down at idle or stay steady? If it stay's steady you may just have a worn motor mount. Have the truck hooked up to a good diagnostic scanner and watch the RPM's for a drop in RPM's to see if there is a slight misfire.

 

Daniel

[ChevyOwner4054]

You might also check the Idle Air Control sensor. It may have carbon build up and can be cleaned with some mass air flow sensor cleaner. I had a buddy whose dad put a custom air flow kit on his truck and it started messing up so that also should be considered. I could not tell if you said you changed the cats but if not, www.rockauto.com will have better priced cats than O'Reilly's or Auto Zone. I had to change my cats and it worked out for me. I used the brand called Walker Emissions. Hope this helps.