Could someone please help me diagnose my caddy?
Last November, I took my car in to the dealership for the following problems:
1) Vibrations when lane changing on the freeway. My guess was

wheel bearings) They said that wasn't the problem, they state everything is fine......As of today, it still vibrates.
2) My car bogs, hesitates, backfires when I step on the gas. They replaced the ISC motor and put in a new throttle body.......as of today it still bogs, hesitates, and backfires when I step on the gas.
Anybody have any ideas. I am used to working on Fords (Merkurs), I didn't think it would be this hard for a dealership to diagnose. I'm sick of being taken to the cleaners for crap service. I've taken it in 3 times already and each time came back with the same results. Do they actually QC their work? Are there ways to read codes on Cadillacs? Any help would be much appreciated.
AJ