Back up your map. Load up TuneEcu and add 5% more fuel to cells in L2 table around 1470rpm +/-1 one row and 380 to 420 hpa That will make your front richer. Don't mind the numbers on my table. I'm running 1190 TB that has higher flowing injectors. Load it and idle the bike. No need for 15min idle. You should immediately see a difference. Try your IR temp sensor on the same spot. Forget about measurements too far from the head. Clean the header a bit, no caked up mud should be there. Now point the laser to somewhere about 1" from the headers. Do this before and after making the changes to your map. Take measurement when bike is fully warmed up. Let us now what happens. So did that ebay TB was exactly the same? If so ,that nukes my initial thought that the front injector was partially clogged. Widebands are great investments. PLX had the cheapest last time I checked. Edit: have you checked your fuel filter lately? I was reminded of this ready other thread just now. It could be that with less pressure everything got leaner.