I have a 2000 Sierra with a 5.3 in it, I was wondering if a failed egr valve could be causing a surging in the motor at about 1200 rpm. It also has a rough idle and 85000 miles on it. Also there is a ticking that sound like air being pushed out from under the hood cant tell were, but you can hear it when your like 10 feet away, sort of like a vacuum leak. Any info. will help. Thanks.

 

Yeah thats it! My blockoff plate was leaking on mine and i heard the exact noise. If you have tuning software, dont replace it, just take it off and disable the EGR tables and codes in the PCM, that should take care of most of your problem, if thats the only thing wrong.