I just went through this with my loader (different brand but the crud under the pedals doesn't care about brand).
Like you, my pedals didn't feel the same either and oddly enough it was the left pedal that felt the worse of the two. I removed all the sheet metal that covers the linkages and then went to work with a long screwdriver and a shop vac. The dirt was caked under the pedals so hard that at times I thought it was cement that had gotten under there somehow.
As I dug through the hardened mixture of rocks, dirt and oil, the shop vac picked up the debris. It took about an hour but I did get most of it out. That's when I went for the power washer. As long as you are careful not to point that dang thing at any seals the power washer does a fantastic job of cleaning the linkages and the bottom of the loader under the peddles. It's worth repeating though... be very careful where you aim the stream of water and never point it at any seals.
After the bottom dried I coated everything with some light oil (WD40) and my pedals are back to normal.
I don't know if any of this is applicable to your machine but it worked miracles on mine.