Hello everyone, i am new to the forums, and i would like to say thank you for letting me join. I have a kinda serious issue with this tractor. I have a 2004 TZ18DA, it is a diesel as everyone knows, my issue is when you are mowing with it or just pushing snow, or doing light work with it, after about and hour of running or so its idle will stumble down next to nothing and almost die. You could just be cruising along and running at top r.p.m. and it will stumble down to about idle and run really rough. It has to be running for a while to get it to do it. I have replaced both fuel filters, and air filters. We are using good fuel, the same fuel i use in two of my diesel pickup trucks. i have ran some power service through it with no results. I took it to the local New Holland dealer and they had the tractor for a week and couldnt duplicate the problem. I am running the tractor on flat ground also, so all fluids should be level. Dealer has no idea what it could be, i just know that when it starts doing it, if you want it to stop it, you have to shut it of for an hour or so, and it will run fine for about another hour and start all over again. We really love this tractor, dont want to get rid of it but if i cant solve soon i will have no choice. Thank you in advance.