$17 fixed it. Don't forget the WIRES
 

After spending $275 for an ignition coil I may or may not have needed, what fixed the old beast was a $17 set of PLUG WIRES!!! and 35 minutes of my tiime.
I didnt have time to fix the Bonne so I dropped off the car at the local Chevy dealer and told them of the rough running during cold start. Car would run fine after reaching temperature however.
Two days later, same thing !!
Did all the recommended throttle body maintenance stuff recommended by our great members - IAC cleaning, throttle body cleaner, EGR, etc etc etc.
I would recommend that if your plug wires have over 35,000 miles, change them out. Or most definitely change them when you put in new plugs. Wish I had the $275 back.

Dealer charged you $275 to replace the coilpack ? I would have a few words with the dealer. Sounds like about $100 for a "diagnosis" that was wrong. Hope you kept the old coilpack.

The Chevy dealer is a customer of mine so I don't want to be to harsh on them. And I don't doubt that the coil pack was weak because in has been in the car for the 10 yrs I've owned it. But regardless, you think they would have done a few more things to make sure the problem would'nt reoccur.

Having had a dealer tell me we had a bad oil pressure guage when two cam bearings were sitting in the bottom of the pan, my opinion of incompetance is less charitable. Can understand if willing to eat the cost for a customer, my concern is that he'll just to the same thing to the next poor schmuck - I do not believe in encouraging behavior like that.

My experience with coilpacks is that a weak one will show up under closed loop (lean)/ low rpm/ high load conditions (say 50 mph up a slight grade with the trans locked up and not a high idle/ open loop/ extra rich for warmup condition

what brand of plugs and wires so you guys suggest?

Keep it simple and stay with the AC stuff. I've been using AC plugs and wires for years with good results. Most people on this site will recommend that you do NOT use BOSCH in your Bonny.

I use AC Rapidfire #14 plugs in my cars with 3800s but all now have Delco ignitions. See my web page for more than you ever wanted to know.