Need help, 2009 GSXR 750 misfiring/low power

Baklava

New member
Aug 17, 2019
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Hello to everyone, new member here
so i have a 2009 Gsxr 750. bike has 9500 miles
list of mods: Two brothers slip on, set valve removed, cat removed, k&n intake air filter, and PC5
the bike has been professionally tuned at a local powersports shop mainly for suzuki sport bikes. bike has been dyno tuned to produce 140 hp to the rear wheel. bike feels like a rocket. i am having a major problem. The other night i was going to my gfs house on the parkway, average speed of 90 mph. i stopped by a gas station and got premium 93 gas. i left my girlfriends house around 2 am. it was around 84 degrees. took the parkway down to another main parkway, average speed of 150 mph. upon slowing down to get on ramp to merge to the second parkway, my bike started to sound like a Harley. sounded like a heavy misfire. i pulled over and it wasidling very rough. barely any power. i tried revving it and it hesitated to go above 4k. i rode the bike home about 14 miles doing 70 and cruising. i decided to bring the bike to my shop, were auto repair mechanics, and the bike was still shitty. passed 8k rpm, the bike takes off and no issues. under that, it idles bad and runs rough. i checked plugs, coils, fuel pump, fuel filter, pair valve, tps sensor -C00, goes up when i rev slightly. i removed injectors and cleaned them. checked plugs for spark. NO FI light is on. tested coils. i am stuck at this point. i tried switching back bikes ecm and removed pc5, still did the same thing. i have no idea what the problem may be, any help will be appreciated. thank you in advance