I know things... A lot of things.
Join Date: Feb 2015
Motorcycle: GSXR 750 K4
Re: 05 GSXR 750 Intermittent Problems
The K4/5 has completely manual idle speed adjustment, and too low idle speed might indeed be causing the problem, if it weren't for the bucking at low speeds. I'm under the impression that fueling relies more heavily on the TPS at higher engine speeds/loads, so I'm not sure whether I'd consider it a prime suspect. (It would also likely throw a code if it made intermittent connection. Keep a lookout for FI flashing on the dash and keep in mind that codes are recorded as they're detected and are lost when the ECU is powered down, so C00 at one particular instant doesn't necessarily mean you are ok.)
The IAP sensor on the other hand should come more into play at lower loads, and vacuum leaks could well depend on temperature. I'd suggest waiting for the problem to appear, then disconnecting the IAPS to check if it goers away. If it does, the vacuum lines would be the first thing to check.