Should I worry about this
 

Hello everybody
When I get in my car in the mornings or after the car is been park for a while I always wait for my RPM's to drop to normal idle before I engage in gear but in a couple of ocassions somehow because of haste I had shifted the car into reverse before the rpm's drop. All hell breaks loose. ESP warnimg light comes on transmission hesitates before it engages and shifts erratically when in drive,and of course I have to park it, thats when the engine idles goes crazy and starts to shake the whole car.I have to turn it off and restart it then everything is back to normal like it never happend.Whats going on is it like waiting for a computer to boot up before you can use it.I hope its me.Does anybody knows.

Damn, how high are your rpms?
Sounds like it simply broke a tire loose, but I would think your idle would really need to be up there to do that. I'd say try not to do that anymore since it sounds kinda harsh (if it feels harsh, it IS harsh on the parts).
I imagine holding the brake down extra hard would prevent wheel spin, but it will be even harsher on the drivetrain.
Hopefully someone will chime in on how to reduce that idle speed, because I don't know how.

you definatly have an idle problem which you should address before breaking something (Transmission, flex disk, half shaft or more)
There's no computer to boot, there is no wait necessary for the idle to stabalize at the normal RPM.
If everything was normal, you would start the car, and by the time the oil pressure is up, idle should be low enough you can shift to D or R before "All hell breaks loose"
defective/dirty Idle valve, vacuum leaks, sticking accelerator linkages, faulty idle switch and many other causes are possible.

worry
 

The thing is.
Everything works normally if I wait for the Rpm's to drop. no problems at all,the rpm's are at 1500 when cold and it takes no more than 15 seconds to drop depending on the ambient temp.I can safely shift into gear when the rpm's are below 1000 but anything above that and the car acts up from the engine, transmission to rear end,not as radical as breaking a tire loose but enough for me to have to shut it off and start again.
has anybody experience this before? The car is a 1999 SL 500 with 52,000 miles.I don't want to break anything,I love this car and this is a great concern to me.

I normally will give a few soft taps on the GO Pedal to get the RPM's to drop more on my 2003 C230. The 190E does not idle as high when cold and I tap the gas twice for some gentle revs, to like 2500RPM then all is good. The C is a Standard shift so it is not as much of an issue, but I always give a few pumps of the gas before taking off, due to me not wanting excessive clutch wear if I can help it!

1500 isn't too bad. Maybe your tranny is engaging to fast, sometimes trannys will do that if a passage is blocked or accumulator is stuck. I've had trannys chirp the tires during normal driving because of this.
If it were my car I'd change the fluid, then if needed try some tranny "fix" in a bottle. The bottle fix stuff helps clean and free stuck parts, I think it's just solvent, but it can fix problems.

OVP relay if its a W124 ?