2003 Nautique 196 Excalibur 330 engine missing

[PDK]

Recently the engine is hard to start after it is shutdown warm. Trying to restart, it backfires thru the air intake. It will start if I open the throttle. The IAV is and throttle position sensor is new. The rpms swing around at idle and few hundred rpms at 2200. Going to check fuel rail pressure today.