Lately I've been seeing a problem with my 03 VIII now that the hot weather is here. When my AC is on the idle becomes rather rough, sputtering with a miss every few seconds; not quite to the point of stalling the motor but it tries. Switch the AC off and within 15-20 seconds or so the idle smooths out and it seems to run normally. No CEL's get thrown (so far).

I recently got the car back from getting a new clutch, I don't know if they could have messed something up. I pulled and checked all the plugs, cleaned, gaped and put them back in. At first I thought I had it (letting the car warm up in the garage), but its not until I drive the car and everything gets heat soaked that the problem shows up.

 

Could be the compressor is on it's last leg. Mine started going out similar to your description

 

One thing I've noticed about this gremlin is that if I start the car up cold and turn the AC on, the problem really never materializes. Turn the car on hot and its right there: the random miss at idle. Its been throwing a CEL every day on the way to work at the same spot on the highway. I need to see what's that code is. I already know my car doesn't like my high flow cat, but that only throws a CEL every week or so. But then again it is hot out.