This one has me boggled. My 2003 is equipped with a TC 88 A. It has stage one, a V&H Fuel Pack, Screaminf Eagle Air Intake, V&H true duals and slip-ons. No other modifications have been made since approximately 15,000 of its current 46,000 miles.
On a very hot day, I recently notice d my speedo acting eratically and then falling to zero, my signal indicators would not shut off automatically and I could not hold an idle. This happened after approx. 80 miles of riding.
From then on, it has become a constant event, as described and only happens when running hot. Starts off fine then 60 to 80 miles down the road, idle is lost. This far I have replaced the sensor for low end idle (next to the oil filter). An intake air leak has been suggested, but doesn't sound right if it takes 60 miles or so to expose the issue. My guess is ECD that somehow gets goofy after that amount of time on the engine.
Looking for help. BTW, I am not throwing any codes, although the engine light has come on a few times, only to shut itself off. I have also run without the fuel pack, same issues.
Help!

 

Does your bike have the maxi-fuse or the circuit breaker?

 

Check the grounds inside the fairing. It turned out to be my problem.

Rick

 

Check battery conections, battery, and grounds in the fairing as sugested above, and main ground. Sounds like a battery or connection issue.

 

Might also be a good idea to pull the speed sensor and clean the tip. A dirty speed sensor can cause the probs you describe with your speedometer...

 

As CroK said the speed sensor is the source of your speedo & turn signal problem, the auto cancel on the signals is speed sensitive, thus if speedo reads zero it thinks you're sitting still. I don't know if that has any connection with your idle problem. Sometimes you can get by with just cleaning the speed sensor, but it will need to be replaced eventually.

 

Dealer thought it was the speed sensor causing the issues with my speedo but it wasn't. I had the same symptoms as the OP and after 2 sensors and a speedo it still wasn't fixed. I found the ground problem while removing the inner fairing for paint. I removed the grounds, scraped the powder coat off to bare metal put a coat of copper shield on and reinstalled the grounds. I haven't had a problem since (2 years). It may be your sensor but it very well could be something else such as a broken wire or bad ground and yes the speedo issue will affect your idle, at least it did on mine.

Rick