99 Silverado C2500 rough idle

[alabbasi]

All,

I bought a 99 3/4 ton Silverado work truck. It's a one owner work truck that I picked for cheap and has about 160k miles on it.

It's not a bad truck,it looks like it's done a few rounds with Joe Frazier but that's OK

It's got a vortec engine which seems to have a rough idle. I replaced the plugs which did not help and I squirted carb cleaner around the intake in search for vacuum leaks but it appears that there are none.

It's not throwing any codes.

I'm hoping that I get some insight at what the problem is before I start throwing money at it.

Thanks

Al