1st problem I had was the valve covers leaking, quick fix and only $10.
Another problem were the brakes, a wheel cylinder blew out and I lost all brakes, not just the rear, made it very dangerous.
Things were always falling off the car. The stickers on the outside that said "Monte Carlo SS" were peeling off. The dashboard trim fell off, the console lid broke off, the driver's door almost fell off when a door pin broke. The headliner fell in, the seat recliner broke on the driver's side, and a tooth broke in the passenger's.
The oil pressure sending unit failed and was leaking oil all over the headers that the previous owner installed. It was tough to get to it since it was located on the bottom driver's side of the engine.
The electric choke on the Quadrajet 4 barrel carburater broke, so I had to have my foot on the gas for about 5 minutes to keep it from stalling in the winter when it was cold. Very annoying.
The car was very fast, but it's not as fast as everyone else says. I was drag racing a 1988 Lincoln Mark VII, and it ran circles around my Monte.
My Monte's rebuilt 305 cubic inch (5.0 Liter) V-8 was great for power. Mine had headers, upgraded camshaft, true dual non-catalytic exhaust, and no emission equipment which brought power up from 180 to 209 (tested on a G-Tech Pro), but is still no match for an 1986-newer Mustang with 225-up horsepower and less weight.
I was always burning the tires off the car, even when I wasn't trying to. It had so much power that even pressing the pedal down about an inch would spin the rear tires. It could do the coolest doughnuts (you know, spinning round and round...)
The car was not comfortable. It was always cold in the car, which is not right because it had a kick ass heater in it. The suspension was wavy over smaller bumps and very harsh over heavier bumps, which does not sound like a good handling car. It should be smooth over bumps, but not wavy, and still handle without making the rear end jump over bumps.
I would have much rather have kept my 1981 Cadillac Coupe Deville. It was much slower, but it was very comfortable. I want another Cadillac, but they are all American - which means it will break down. I'm going to buy a Japanese car next.