Took me 11 days to get the greasy film off my plates and it was one dumb thing
For almost two weeks my plates kept coming out with this cloudy grease film no matter how much soap I used, and I was about ready to blame my water heater. Turned out my dishwasher was fine and the real issue was the rinse aid dispenser door was stuck shut, so nothing was sheeting off and everything just dried in its own gunk. I popped it open with a butter knife, ran one cycle with a splash of white vinegar in the bottom rack, and the plates came out squeaky clean on the first try. Now I keep checking that little door like it owes me money. Has anyone else had a dispenser stick like that, or is it just my ancient machine?
Check the float switch too while you are in there. That little plastic piece can get gummed up with old rinse aid and it thinks the door is still shut even after you pop it. Take a q-tip with hot water and wipe the track where the door slides. Mine stuck every few weeks until I cleaned that gunk out, now it swings free. Your machine probably is not dying, it is just dirty in a spot you never see.