Hello i need helps for my bike. The bikes runs great but when i downshift in 1 gears it shut down even i pull the clutch i need to pull the gaz for not shut down but it start well i dont know if it was the idle to low.. i have cherry bomb on it thx

Started randomly and got worse over time. Quad will start easy and idle but will not rev up. Pops and backfires and will die if throttle left open. 1 checked fuel pressure. Good 2 found pressure dropped when throttle chopped at idle. Changed fuel pump with new Honda one. Fuel pressure good...