p1811 wth?

i finally was able to scan my tranny since ive been having slipping, o/d, and shutter issues. has anybody pulled this code before? and what should i do?
i read some where its caused by a decrease or increase in line pressure.(i have a aftermarket pcm) and it may be caused by trash in the valve body, or in the pressure control valve. i have 104000 miles on it and really iffy on doin a flush. so whats up? thanks