Cub Cadet engine is surging
 

Have an older Cub Cadet, has 582 decal on front of tractor. The previous owner wanted it to be some kind of Hot Rod. It had at sometime in the past, equipped with a Kwik-Way loader system. I rebuilt with new hoses and pump, loader works as advertised. Has a different rear axle, model number on plate on axle body suggest it was from a 782! Although the lift (bucket) is fine, new problem seems to be engine rpm is going up and down, surging i guess? When it idles it runs fine, no matter where you put throttle. When it is put in either forward or reverse (had automatic Trans installed by whoever previous owner was), the RPM's go up and down till it stalls while in F/R but not when it just idles. Can anyone help me figure on what is going on here? Spent most of winter rebuilding loader system, but did change motor oil, Trans oil, can’t seem to get front end of CC (engine cover) off to allow me to access engine. Any help with that I could also be appreciated, Thanks for reading this post and any help I can receive along the way.

Sounds to me like it is starving for gas.
You can first try to richen up the main fuel jet but if no help
check for crap in fuel tank, clogged shut off valve, fuel line or filter.
Check that gas cap is venting.
Do you have a fuel pump, is it working.
If still no joy, drop the carb bowl, check for crap.

Thanks for the help Ironman. I wanted to do most of what you have described here today. If i could just disassemble front end to see what i wanna look at. Nothing standard about this machine it seems, but I bought it so I’ll need to figure it out. No mower shop around me, so here I go. Wish me luck! ?

I would follow Ironman. sounds like fuel issue. filter a little cloggie, pump a little cloggie. carb cleaner in the fuel might help.

The 582 was/is gear drive with a Briggs engine.
So a 782 transmission would be make more sense in order to have hydraulics for the loader.
Question is, do you have a Briggs engine, or a Kohler which would have come in a 782??
More likely, it is not the original hood.
What is the serial number on the plate down by the brake pedal??
Is the tractor red or yellow/white??