Too many things to mention...
Rear wheel bearings had to be replaced at 30,000 miles and again at 55,000.
Air conditioner constantly leaked water inside, on the front passenger's feet. Numerous trips to the dealer we unable to resolve this.
Transmission would jump out of 5th gear and into neutral at any random time. This first started around 40,000 miles, and required replacing a vacuum cannister to repair. Same problem occurred at 60,000 miles when I sold it.
Constant grinding noise from under the hood. Suspect it was a bad bearing on some belt-driven device (alternator? AC compressor?) but numerous trips to the dealer were unable to resolve it.
Constantly leaked oil.
A real disappointment of a car. It was very roomy and comfortable; the interior was large and the folding seats added great flexibility. With 4 wheel drive, it handled New England winters with ease. It was underpowered, but the trade-off for that was excellent mileage for a car that could carry 7 people. But it was a mechanical nightmare. It was in the shop for repairs way too often. With only 60,000 miles on it, my monthly repair bills were more than the cost of a new car, which is why I sold it.
I tried to trade it in when I bought my new car, but the dealer said the Colt Vistas had such a poor maintenance reputation that they no longer accepted them as trades.