Having owned mostly older vehicles (76 Chevy Truck, 79 Lincoln Continental, 82 Eldorado) I will tell you this much... Check ALL the electronics... My main problem in owning these vehicles has ALWAYS been the 'luxury' items... Power windows, power doors, power locks, cruise control... In the 90 Eldorado I'd also say to make sure the dash is operating right too... With both my Lincoln and my current Cadi I had MAJOR issues with fixing this stuff... Figuring out if it's a wiring, fuses, motors, computers... Very time consuming and frustrating, plus hunting down replacement parts can be hard as hell too...
I'm about to have to sink about $1,500 into motors alone, and that's not including putting them in...
As far as engine goes, I've never had or seen any major mechanical issues with them. A few of my friends and I were sporting around in various Cadi's for a few years (84 Eldo, 88 Eldo, 91 Brougham), and none of us ever had any major issues with the engines, aside from the usual wear and tear that comes with age and use...
