New poster here...for the past two weeks the sound through my cutout at idle had an almost 'put put put' noise, coinciding in a loss in power, especially down low. This was around the same time I did plugs and replaced a few wires that were cracked and burned on the passenger side header. Long story short, after much hair pulling, a shop diagnosing me with an exhaust leak from my collector, and tinkering on the thing, I went ahead and replaced all the wires this morning, only to find a previously good wire, totally cracked and burned through. Lesson learned, don't go halfway with wire changes, even if they 'seem' good. Just save oneself the trouble and do it all and rid yourself of one less variable. (By the way, there was no exhaust leak anywhere, I think the dude just wanted to tell me something was wrong, because he really didn't know.) Just wanted to post my story in the event someone was/is having the same symptoms as myself, and my fix to the problem.

 

Im having the excact same trouble, I just installed a motor from another car,It ran perfect when It was in the other car, I pulled the motor out, put new plugs and wires in it, then I installed the motor in my car, now it has a bad low idle miss, it seems to clear out at higher rpm's. I do have a small exhaust leak, I'm gonna get the leak straightened out and go from there.
By the way, Im workin on a 96 Fleetwood with the LT1. I posted this problem on the Cadillac forums and nobody seems to have any Ideas, but most of the guys on there take their cars to the dealership for any problems, but you guys all seem to have alot of knowledge of these LT1 cars. any help would be appriciated

 

The only thing I can really suggest is to ensure all the plugs are on tight, that the wires are on securely, and basically double check your connections. If none of those suffice, then I'd say watch the engine run at night, and watch for arcing, either from the wires or the coil, then check the coil/coil wire, plug wires etc... with a multimeter, ensuring they're reading right. I know it seems like a laundry list, but you're trying to keep yourself from getting into the expensive stuff (read: optispark) over something trivial, like a burnt wire in my case. This is a great board with a lot of great tech stuff, including references. I use the heck out of the search function.