Runs fine at open throttle, but when blade engaged, or going uphill, or any kind of load, begins to backfire intermittently. Also has a slight surge. Ideas?

I bought this tractor new in 2005. It has been a good tractor. I am having problems with the Screw Thdrol (part #143). It is a part that was attached to the frame via a few tack welds. The newer versions may be different. This part holds the idler pulleys that controls the tension (Bracket Asm...

Check out my GT5000 pics or at least how it looked when I first got it home! :D And one pic of my older (but awesome 19HP - 1996 model) --- Still have both and use em plus my Ford 8N in the 3rd picture at the bottom (for the tough bushhogging work) Hope you like em. -Andy <img...

I really like my GT5000. --- Looks like according to some people the hydro and the 25HP Kohler is overkill and a waste of $$$. I really love my tractor. Little usage thus far but one incredibly powerful and well-built machine so far. Any comments on this model so far? Problems? I did...