Rough idle at Start, please help...

[BigAlVB]

Hi everyone! My '91 Sub w/ 5.7 L FI motor is running rough when I start it up. Only lasts a minute or two and usually, but not always, when its cold and/or damp. I've noticed at times it idles higher than I feel it should--I don't have a tach, just a "seat of the pants type feeling." Also, at times (very intermittently) my Check Engine light comes on. When I shut the truck down, it goes off and doesn't come back on. Seem s to run out fine on the road.
Any help, sugguestions, whatever will be appreciated.

I've been busy! I had a 2.5" suspension lift with 8(!) leaves on the front, and they were going into a negative arch! Yep, it rode like he#$! Replaced it with 4 leaves by Superlift (tapered Softride) and what a difference! Also all of my ball joints were "frozen up"and my tie rod ends were shot so I replaced them with greasable ball joints and new tie rod ends. Rides almost like a new truck now.