Moose, your dealer has NOT read the service manual and he is added to my list of Kymco dealers that do NOT know their product (and other really inappropriate descriptions....). You / the tech MUST initialize, repeat, INITIALIZE anytime the TPS, ISC and anything are replaced in the EFI system. This is an animal that you cannot, repeat, CANNOT, just throw parts on to "fix" problems. Initialize is: run/stop switch in RUN; key OFF; open throttle to stop; key ON (DO NOT START); after 8 seconds, throttle closed, key OFF; Then start engine normally, idle should be 1600 rpm +/- 100 rpm. Ride around awhile to see if throttle behaves normally. If not, do INITIALIZE again (Bill Gates fix, kinda). Your "dealer" could have done this up front and would not have had to do the parts thing most likely. Since the parts did not fix the problem I am led to believe that initialize would have fixed it originally. I have had to do this on my DT300i several times since new 'cause of goofy idle. Runs really well and has done so for a long time since last initialize.
Karl
PS: Does your "dealer" even have a Kymco analyzer?