Sounds like several problems
What year is your car
Check all basic stuff first such as plugs wires filter etc.
On the smoke issue make sure you check the engine oil to see if it is milky or if there is any milky rsidue on the oil cap. I am having you check this to see if you have a headgasket problem you said it was white smoke and low power trans fuild can appear white but it will have a blue or grey tint to it. If the smoke fills up several lanes of traffic then maybe it is the modulator but if it is just a small cloud of white smoke it could be the headgasket which would help explain your power problem. Oh yea does the car get hot?
The gear shift selector being sloppy is caused from the bushings on the shift linkage going bad The car should always starts in first even though your selector only goes to 2nd
The high idle can be many things is your ABS light on.
Check the fuse or fuses in the OVP relay. The OVP Relay is behind the battery next to the Modules and looks like this
I also attached a schematic
Also you may need to start checking vacuum lines there are some that go to the ICV(idle control valve) that are common to go bad from age or the valve could be going bad
Check some of this and let me know what you find. If you dont have on yet get the W201 manual here
Modified Technologies, Inc | Enthusiast Gear it is a large file to down load but it will be very helpful for ya