Adjusting Hydro Creep
 

My son has a 149 and the tractor gets faster and faster as you drive unless you hold the hydro lever. Is there any way to adjust this? I remember my dad having an old MF 12 that did that.We adjusted that by the manual but never did stop it.We made a stop to keep the lever from moving.

sounds like it needs the trunion repaired.
http://cubfaq.com/trunionrepair.html

Wow thought it was an easy adjustment. Guess i will keep holding the lever.

On mine if i held the lever in one place it would still speed up like it had a mind of it's own and it was the trunion. on yours im not sure without seeing it.
Maybe it is just a speed adjustment.

http://cubfaq.com/hydronut.html

Yeah, just sounds like you need to tighten up the adjuster a little. There is also a plastic bushing that may need replaced if the adjusting doesn't do the trick. A friend had to replace his after tightening the adjuster didn't work.

MY 149 did the same thing, it happened overnight, all of a sudden it would just run away. Checked the trunion and it looked good so I just tightened the adjuster on he bottom of the hydro lever. Its a small allen head cap screw. It works fine now. That and the neutral adjust are the two easiest and best things to do to your hydro.