I´m trying to make my own motor driver, and this is what i could do until now by following some tutorials.
Happens that i can drive the motor in both ways with no problem!
If i connect the servo, and the motor, they both run for a couple of seconds and then stops... i think i should use a power supply for the motor but i´m lost in here..
My bet is thatyou are drawing (much) more current than Arduino can supply. Almost any motor, even the smallest will draw more than the 40mA that one Arduino pin can source, at absolute max.
As you suggest yourselv, you need an external powersupply for at least the DC motor, probably also the Servo.
Hi MikMo! Thanks for replying!
Yes, i think that i should give the motor another power supply, i just don´t know how to do it...
for example: i power the arduino with a 9V battery.
if i want to power the motor with a racing pack battery of 7.2V 2000mAh how and where should i connect it?
its working for a couple os minutes non stop, non burning... smoothly!!! 
i´m very happy
i´m using another 9V battery with a 5V voltage regulator for powering the motor, and both arduino and L293D are sharing the same GND .. the other 9V powers the arduino, and the arduino powers the servo.. in theory i still can connect one more motor
if anyone see something not correctly i apreciate advice!
i know it´s a mess, i´ll make this look better i promess 