not sure if i can help but there is a great trouble shooting section in my manual near page 60-ish i am about to start there for the same reason you are having with speed super slow and hills that come to a crawl on.
http://taylordunnparts.com/manuals/C...SN151285UP.pdf
it sounds like we both have issues with the coil resistors that creat the correct voltage flow for the speed needed. -like i said i am not sure but i have my hill creeper for 30 days now and begining to learn more about the cart.
http://taylordunnparts.com/manuals/C...SN151285UP.pdf