Yosh Box/PC III Question

I have a DL1000K5 that has had the typically discussed FI problems at lower RPMs. I am the second owner of the bike which just turned over 5000 miles. The first owner had installed a PC III on the bike which never seemed to solve the running issues. When I took the bike to a local Suzuki dealer to discuss what they might do to help with the problem, I was told about tuning using a Yosh box. They told me I should disconnect the PC prior to doing the Yosh procedure, which I did. The bike now runs very well except for some sputtering/stalling out while at idle. Although the engine runs without hesitation above idle, my fuel mileage has suffered a lot. Before the Yosh tuning, I was getting 39-42 mpg, however, I now get 28-30. Can anyone tell me if this is normal and if it can be retuned using the Yosh to still run smoothly without the drastic reduction in fuel mileage? The bike has stock pipes and air filter. I guess my other option is to reconnect the PC and have a custom map done at a tuning center. I'd like to know what sort of fuel mileage others get and would really appreciate any suggestions on fixing this problem.