if it turns out it's your seat comps i've got two sitting on my shelf here that i'd sell extremely reasonably. I got them with two newer model seats that i put into my 83 300SD. the seats came out of a 88-91 W126. I'm not positive if they work or not, but like i said i'd let them go very reasonably as i have no need for them whatsoever. The fact that both of your seats are acting up makes me leary to think its the computers though.
Ryan