door locks slow in back but fast in front?
 

I have a 300 sel 1990 and the door locks in the back are getting slower and slower, front ones work great Oh and the auto locks ( key fob does not actuate locking or unlocking, and window on drivers side will not roll down...one problem or another pain in the ass spend a fortune mercedes only..itll cost 500.00 to fix deal? I love this car but it is just getting worse now there is a clunk when the tranny shiftsdoown when coming to a stop, and a moan from the front wheel area when turning right but not left. Chainged to synthetic powersteering fluid did not help.....help me loosing mind read so many posts my mind is numb, must start stealing parts AHHHHHHHHHHHHHHHHHHHH

Any help on dianostics would be a help so I don't start hitting it with a wrench...Thank you