Hello all. New to this so please bear with me. I have a Kubota L5450 that I purchased second hand. Up until recently it has been performing very well, but recently it has started acting up. What happens is that it will run just fine cold, but when the engine gets up to temperature it starts hesitating and acts almost as if it is fighting back pressure. Any suggestions as to where to start looking. I have to say that it probably needs a new air filter, but fuel filter has been changed several times to be certain there was no crud blocking the fuel flow. As you can tell, I have little to no experience with diesel so any starting point for me would be appreciated. Thanks.