2005 Yamaha F90TLRD EFI motor surges from about 400rpm up to 1500rpm and then will eventually die. It will usually start right back up and start surging again. Runs fine Midrange and top end. Sometimes it will run fine for the first 30 to 60 seconds then starts surging. I have replaced VST filter and cleaned VST, Cleaned injectors, replaced ISC Valve, tested TPS and Intake Pressure sensor. YDS does not show anything out of spec. Any other thoughts. I am pulling my hair out on this one.