So cleaned the throttle body, and put a bottle of redline fuel system cleaner in the tank but I'm still getting a rough idle. I'm thinking about clean the MAF next but I'm not confident that will solve the problem. Any suggestions?

 

how rough is it, they dont all idle perfectly. especially the 4.8

 

Idle air control motor?

 

Honestly, it sounds like your intake manifold might have a blown gasket. Is it setting of the CEL. The composite plastic that GM uses is very prone to warping and bad gaskets. I had the same problem with my 03 5.3L. The Idle was very erratic it would get so bad that the motor would actually stall and die. Thats just my 2 cents. hope it helps

 

I have heard that the 4.8 does tend to have a rough idle. It's not horrible in the sense that the Tach doesn't jump around but it's still an annoyance. The truck only has 17000 miles on it. This is my first chevy and none of my trucks in the past had this problem. Would it be worth taking to the dealer or is that just a waste of time?

 

i have a 283 in my 89 chevy and i also have a digital RPM and my truck never stays in one place. it will go up and down a good 400 rpms some times. theres days when it gets cold that i start my truck and it wil idle to 1000 then go down to 300-500 rpms, some times it dies.... all i do is just let her warm up for about 15 minutes before i drive her. if you dont agree with that then look at you fireing system: cap, rotor, distributor, wires, gap, plugs...