hello everyone! This is not for me but one of my buddies. He's got a problem with his bike as he says below. Anyone have any ideas? Thanks for your help!

I had a very knowledgeable guy do the following repairs to a 01 GSXR750:
-change spark plugs -clean airfilter -replace a fan relay -and he basically tried to diagnose any other issues with the bike.

Now the history of this bike; I bought it 2 months ago. It was not taken care of by previous owner, the bike would run strong but would not go over 10K in 1st gear and would not go over 12-13K in any other gear, and the FI light would come on sporadically, so I know the bike has issues.

This "mechanic" told me the SVTA is probably bad because the butterfly valves are stuck open, but I still have yet to get a C28 code. Actually the bike has never put out a code. He also told me the fuel pump is not in optimal condition- it works, but he thinks it should be replaced, I am not sure the exact reason.

I got the bike back the other day and it runs like ****- like it has fouled plugs or water in tank. It is very sluggish. I told the guy and he tried to help. We found out the battery was close to dead, so it was replaced. Also I disconnected the Powercommander because the guy thought it might be shot.

Here is how the bike behaves now. When I turn the key there is hear a loud buzzing noise for 1-2 seconds coming from my fuel pump (not certain since haven't taken tank off), which wasnt there before. Everygear the bike is very sluggish, but if I keep the throttle wide open it slowly climbs through the RPM's and when it hits 7-8K RPM the bike takes off and runs like it should (with lots of power).

Can someone tell what I should look at next to try and diagnose this issue?