So, I was driving home the other day in my 99 Silverado 5.3 z-71 and after getting off the interstate and coming to a stop, it sounded like it wanted to die. I got on it and ran fine; however, when sitting at idle it felt like I had a pro-comp cam in there or something, it was loping and shaking and just sounded real bad. I ended up sitting in traffic for 30 minutes and it would smooth out for a few minutes every now and again after moving for a little bit and then it would get real rough again. I pulled the code and got a random misfire, I did tune up about 4 months ago, could plugs be hunks of junk, idle air control valve, mass air flow sensor. It hasn't done it since Saturday maybe it only does it after being run for a good little while. I am not sure what to change because I don't have anything specific. Does anyone think that if my idle air control valve is bad and made my idle real rough that it made it so rough that it started to misfire? I appreciate the help

 

First thing to do is check for codes, second is to check for vacuum leaks...post results and we'll go from there...

 

Okay thanks a lot, I will go get some carburetor cleaner and look for a vacuum leak.